Bump actions/setup-python from 5 to 6 (#828)

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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Justus Magin <keewis@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/main.yaml

@@ -29,7 +29,7 @@ jobs:
           fetch-depth: 0 # checkout tags (which is not done by default)
       - name: 🔁 Setup Python
         id: setup-python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
           cache: pip

.github/workflows/release.yaml

@@ -10,7 +10,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.x"
       - name: Install dependencies

.github/workflows/test-integration.yaml

@@ -38,7 +38,7 @@ jobs:
       - uses: actions/checkout@v4
       - name: 🔁 Setup Python
         id: setup-python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
           cache: pip