Drop support of Python 3.9

[candleindark]

The dev version of nwbinspector has started requiring Python 3.10 or above, as can be seen in its pyproject.toml file and out failing test:

Let's drop our support for Python 3.10 to be in step with dependencies such as nwbinspector.

Possible steps involved.

1. Update the Python requirement in pyproject.toml
2. Remove used of Python 3.9 in test environments.

[candleindark]

Ping @yarikoptic

[yarikoptic]

ok, let's drop altogether because dependency will be released soon with dropped support .... my initial diff was

diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index aa01427d..dbebec3f 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -28,10 +28,6 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
 
-    - name: Install hdf5 (Ubuntu)
-      if: matrix.python == '3.9' && startsWith(matrix.os, 'ubuntu')
-      run: sudo apt-get update && sudo apt-get install -y libhdf5-dev
-
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip wheel
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 23486afb..cd620424 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -15,7 +15,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v6
       with:
-        python-version: '3.9'
+        python-version: '3.10'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index bcf7673e..8d6f56cc 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -50,7 +50,7 @@ jobs:
             python: 3.13
             mode: obolibrary-only
           - os: ubuntu-latest
-            python: 3.9
+            python: 3.10
             mode: dev-deps
           - os: ubuntu-latest
             python: 3.13