Update ubuntu to 26.04

[weiji14]

https://documentation.ubuntu.com/release-notes/26.04/

TODO:

• Bump ubuntu version in base-image
• Add note to README.md mentioning new version

Previous upgrade at #617

[weiji14]

Seriously, tensorflow error-ing again? Logs at https://github.com/pangeo-data/pangeo-docker-images/actions/runs/25196448072/job/73878042510?pr=651

=================================== FAILURES ===================================
___________________________ test_import[tensorflow] ____________________________

package_name = 'tensorflow'

    @pytest.mark.parametrize('package_name', packages, ids=packages)
    def test_import(package_name):
>       importlib.import_module(package_name)

tests/test_ml-notebook.py:19: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
../conda/envs/notebook/lib/python3.12/importlib/__init__.py:90: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
<frozen importlib._bootstrap>:1387: in _gcd_import
    ???
<frozen importlib._bootstrap>:1360: in _find_and_load
    ???
<frozen importlib._bootstrap>:1331: in _find_and_load_unlocked
    ???
<frozen importlib._bootstrap>:935: in _load_unlocked
    ???
<frozen importlib._bootstrap_external>:999: in exec_module
    ???
<frozen importlib._bootstrap>:488: in _call_with_frames_removed
    ???
../conda/envs/notebook/lib/python3.12/site-packages/tensorflow/__init__.py:40: in <module>
    from tensorflow.python import pywrap_tensorflow as _pywrap_tensorflow  # pylint: disable=unused-import
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
../conda/envs/notebook/lib/python3.12/site-packages/tensorflow/python/pywrap_tensorflow.py:37: in <module>
    self_check.preload_check()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    def preload_check():
      """Raises an exception if the environment is not correctly configured.
    
      Raises:
        ImportError: If the check detects that the environment is not correctly
          configured, and attempting to load the TensorFlow runtime will fail.
      """
      if os.name == "nt":
        # Attempt to load any DLLs that the Python extension depends on before
        # we load the Python extension, so that we can raise an actionable error
        # message if they are not found.
        if MSVCP_DLL_NAMES in build_info.build_info:
          missing = []
          for dll_name in build_info.build_info[MSVCP_DLL_NAMES].split(","):
            try:
              ctypes.WinDLL(dll_name)
            except OSError:
              missing.append(dll_name)
          if missing:
            raise ImportError(
                "Could not find the DLL(s) %r. TensorFlow requires that these DLLs "
                "be installed in a directory that is named in your %%PATH%% "
                "environment variable. You may install these DLLs by downloading "
                '"Microsoft C++ Redistributable for Visual Studio 2015, 2017 and '
                '2019" for your platform from this URL: '
                "https://support.microsoft.com/help/2977003/the-latest-supported-visual-c-downloads"
                % " or ".join(missing))
      else:
        # Load a library that performs CPU feature guard checking.  Doing this here
        # as a preload check makes it more likely that we detect any CPU feature
        # incompatibilities before we trigger them (which would typically result in
        # SIGILL).
>       from tensorflow.python.platform import _pywrap_cpu_feature_guard
E       ImportError: libtensorflow_cc.so.2: cannot enable executable stack as shared object requires: Invalid argument

../conda/envs/notebook/lib/python3.12/site-packages/tensorflow/python/platform/self_check.py:63: ImportError
_____________________________ test_jax_tf_together _____________________________

    def test_jax_tf_together():
        """
        Sometimes this import fails due to sharing private symbols.
        Complicated long story, but it is better to ensure they can coexist
        """
        import jax
>       import tensorflow

tests/test_ml-notebook.py:32: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
../conda/envs/notebook/lib/python3.12/site-packages/tensorflow/__init__.py:40: in <module>
    from tensorflow.python import pywrap_tensorflow as _pywrap_tensorflow  # pylint: disable=unused-import
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
../conda/envs/notebook/lib/python3.12/site-packages/tensorflow/python/pywrap_tensorflow.py:37: in <module>
    self_check.preload_check()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    def preload_check():
      """Raises an exception if the environment is not correctly configured.
    
      Raises:
        ImportError: If the check detects that the environment is not correctly
          configured, and attempting to load the TensorFlow runtime will fail.
      """
      if os.name == "nt":
        # Attempt to load any DLLs that the Python extension depends on before
        # we load the Python extension, so that we can raise an actionable error
        # message if they are not found.
        if MSVCP_DLL_NAMES in build_info.build_info:
          missing = []
          for dll_name in build_info.build_info[MSVCP_DLL_NAMES].split(","):
            try:
              ctypes.WinDLL(dll_name)
            except OSError:
              missing.append(dll_name)
          if missing:
            raise ImportError(
                "Could not find the DLL(s) %r. TensorFlow requires that these DLLs "
                "be installed in a directory that is named in your %%PATH%% "
                "environment variable. You may install these DLLs by downloading "
                '"Microsoft C++ Redistributable for Visual Studio 2015, 2017 and '
                '2019" for your platform from this URL: '
                "https://support.microsoft.com/help/2977003/the-latest-supported-visual-c-downloads"
                % " or ".join(missing))
      else:
        # Load a library that performs CPU feature guard checking.  Doing this here
        # as a preload check makes it more likely that we detect any CPU feature
        # incompatibilities before we trigger them (which would typically result in
        # SIGILL).
>       from tensorflow.python.platform import _pywrap_cpu_feature_guard
E       ImportError: libtensorflow_cc.so.2: cannot enable executable stack as shared object requires: Invalid argument

../conda/envs/notebook/lib/python3.12/site-packages/tensorflow/python/platform/self_check.py:63: ImportError

conda-forge/tensorflow-feedstock#455