build(deps): 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] <[email protected]>

Author: dependabot[bot]

.github/workflows/python.yml

@@ -35,7 +35,7 @@ jobs:
       - uses: actions/checkout@v5
         with:
           fetch-depth: 0
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
       - run: pip install -r requirements_ci.txt
@@ -63,7 +63,7 @@ jobs:
       - uses: actions/checkout@v5
         with:
           fetch-depth: 0
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: '3.13'
       - run: pip install build~=1.2