[5.1.x] Refs #34900 -- Added Python 3.12 to classifiers and tox.ini, and used it in GitHub actions.

Backport of f07eeff3a2d7ff0955410bf7e3f1ff197ef1ecf7 from main.

.github/workflows/docs.yml

@@ -30,7 +30,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
           cache: 'pip'
           cache-dependency-path: 'docs/requirements.txt'
       - run: python -m pip install -r docs/requirements.txt
@@ -48,7 +48,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
       - run: python -m pip install blacken-docs
       - name: Build docs
         run: |

.github/workflows/linters.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
       - run: python -m pip install flake8
       - name: flake8
         # Pinned to v3.0.0.
@@ -44,7 +44,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
       - run: python -m pip install isort
       - name: isort
         # Pinned to v3.0.0.

.github/workflows/schedule_tests.yml

@@ -19,7 +19,7 @@ jobs:
           - '3.10'
           - '3.11'
           - '3.12'
-          - '3.13-dev'
+          - '3.13'
     name: Windows, SQLite, Python ${{ matrix.python-version }}
     continue-on-error: true
     steps:
@@ -46,7 +46,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
           cache: 'pip'
       - name: Install libmemcached-dev for pylibmc
         run: sudo apt-get install libmemcached-dev
@@ -145,7 +145,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
           cache: 'pip'
           cache-dependency-path: 'tests/requirements/py3.txt'
       - name: Install libmemcached-dev for pylibmc
@@ -181,7 +181,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
           cache: 'pip'
           cache-dependency-path: 'tests/requirements/py3.txt'
       - name: Install libmemcached-dev for pylibmc

.github/workflows/selenium.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
           cache: 'pip'
           cache-dependency-path: 'tests/requirements/py3.txt'
       - name: Install libmemcached-dev for pylibmc
@@ -61,7 +61,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
           cache: 'pip'
           cache-dependency-path: 'tests/requirements/py3.txt'
       - name: Install libmemcached-dev for pylibmc

.github/workflows/tests.yml

@@ -23,7 +23,7 @@ jobs:
     strategy:
       matrix:
         python-version:
-          - '3.12'
+          - '3.13'
     name: Windows, SQLite, Python ${{ matrix.python-version }}
     steps:
       - name: Checkout