Bump actions/setup-python from 5 to 6

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 5 to 6.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v5...v6)

---
updated-dependencies:
- dependency-name: actions/setup-python
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -42,7 +42,7 @@ jobs:
       - name: "Checkout repository"
         uses: "actions/checkout@v4"
       - name: "Set up Python ${{ matrix.python-version }}"
-        uses: "actions/setup-python@v5"
+        uses: "actions/setup-python@v6"
         with:
           python-version: "${{ matrix.python-version }}"
       - name: "Add directories where pip installs scripts to PATH"