Run basic Python 3.13 tests (ray-project#51688)

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## Why are these changes needed?

Now that conda has been released for Python 3.13
(https://github.com/conda/conda/releases/tag/25.3.0), which makes it
possible to use Python 3.13 in base environments, we can run the basic
tests.

## Related issue number

<!-- For example: "Closes ray-project#1234" -->

## Checks

- [ ] I've signed off every commit(by using the -s flag, i.e., `git
commit -s`) in this PR.
- [ ] I've run `scripts/format.sh` to lint the changes in this PR.
- [ ] I've included any doc changes needed for
https://docs.ray.io/en/master/.
- [ ] I've added any new APIs to the API Reference. For example, if I
added a
method in Tune, I've added it in `doc/source/tune/api/` under the
           corresponding `.rst` file.
- [ ] I've made sure the tests are passing. Note that there might be a
few flaky tests, see the recent failures at https://flakey-tests.ray.io/
- Testing Strategy
   - [ ] Unit tests
   - [ ] Release tests
   - [ ] This PR is not tested :(

Author: pcmoritz

.buildkite/core.rayci.yml

@@ -36,6 +36,7 @@ steps:
       - "3.10"
       - "3.11"
       - "3.12"
+      - "3.13"
     env:
       PYTHON_VERSION: "{{matrix}}"
       EXTRA_DEPENDENCY: core
@@ -287,6 +288,7 @@ steps:
       - "3.10"
       - "3.11"
       - "3.12"
+      - "3.13"
 
   # cpp tests
   - label: ":ray: core: cpp tests"

ci/env/install-miniconda.sh

@@ -85,6 +85,7 @@ install_miniconda() {
     (
       set +x
       echo "Updating Anaconda Python ${python_version} to ${PYTHON}..."
+      "${WORKSPACE_DIR}"/ci/suppress_output conda remove --force -y anaconda-anon-usage
       "${WORKSPACE_DIR}"/ci/suppress_output conda install -q -y python="${PYTHON}"
     )
   elif [ "${MINIMAL_INSTALL-}" = "1" ]; then  # Reset environment
@@ -95,9 +96,9 @@ install_miniconda() {
     )
   fi
 
-  if [[ "${PYTHON-}" != "3.12" ]]; then
+  if [[ "${PYTHON-}" != "3.12" && "${PYTHON-}" != "3.13" ]]; then
     # Install mpi4py as a test dependency for Python <3.12; currently mpi4py is not
-    # available for Python 3.12
+    # available for Python 3.12 or 3.13
     "${WORKSPACE_DIR}"/ci/suppress_output conda install -c anaconda mpi4py -y
   fi
 

doc/source/ray-overview/installation.rst

@@ -107,7 +107,7 @@ You can install the nightly Ray wheels via the following links. These daily rele
         `Linux Python 3.10 (x86_64)`_                    `Linux Python 3.10 (aarch64)`_
         `Linux Python 3.11 (x86_64)`_                    `Linux Python 3.11 (aarch64)`_
         `Linux Python 3.12 (x86_64)`_                    `Linux Python 3.12 (aarch64)`_
-	`Linux Python 3.13 (x86_64)`_ (alpha)            `Linux Python 3.13 (aarch64)`_ (alpha)
+        `Linux Python 3.13 (x86_64)`_ (beta)            `Linux Python 3.13 (aarch64)`_ (beta)
         =============================================== ================================================
 
     .. tab-item:: MacOS
@@ -119,7 +119,7 @@ You can install the nightly Ray wheels via the following links. These daily rele
         `MacOS Python 3.10 (x86_64)`_                  `MacOS Python 3.10 (arm64)`_
         `MacOS Python 3.11 (x86_64)`_                  `MacOS Python 3.11 (arm64)`_
         `MacOS Python 3.12 (x86_64)`_                  `MacOS Python 3.12 (arm64)`_
-        `MacOS Python 3.13 (x86_64)`_ (alpha)          `MacOS Python 3.13 (arm64)`_ (alpha)
+        `MacOS Python 3.13 (x86_64)`_ (beta)          `MacOS Python 3.13 (arm64)`_ (beta)
         ============================================  ==============================================
 
     .. tab-item:: Windows (beta)

python/ray/tests/test_basic_2.py

@@ -573,7 +573,7 @@ def __init__(self):
 
         def call(self):
             # Record the current thread that runs this function.
-            self.threads.add(threading.current_thread())
+            self.threads.add(threading.get_ident())
 
         def get_num_threads(self):
             return len(self.threads)