⬆️ Upgrade GitHub Actions to Node.js 24 compatible versions

actions/checkout, actions/setup-python and codecov/codecov-action were
running on Node.js 20, which is deprecated and will be forcibly removed
from runners on September 16th, 2026. Updated to v6 across both
ci.yml and code_quality.yml.

pypa/gh-action-pypi-publish is unaffected (Docker-based, not Node.js).

Author: swrichards

.github/workflows/ci.yml

@@ -21,8 +21,8 @@ jobs:
     name: Run the test suite (Python ${{ matrix.python }}, Django ${{ matrix.django }})
 
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
           python-version: ${{ matrix.python }}
 
@@ -36,7 +36,7 @@ jobs:
           DJANGO: ${{ matrix.django }}
 
       - name: Publish coverage report
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@57e3a136b779b570ffcdbf80b3bdc90e7fab3de2 # v6
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
 
@@ -51,8 +51,8 @@ jobs:
     if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
 
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
           python-version-file: 'pyproject.toml'
 

.github/workflows/code_quality.yml

@@ -22,8 +22,8 @@ jobs:
       matrix:
         toxenv: [isort, black, flake8, docs]
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
           python-version-file: 'pyproject.toml'
       - name: Install dependencies