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](https://github.com/actions/setup-python/compare/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>

.github/workflows/ci.yml

@@ -44,7 +44,7 @@ jobs:
             .tox
             ~/.cache/pip
           key: "${{ matrix.testenv }}-${{ hashFiles('misc/requirements/requirements-*.txt') }}-${{ hashFiles('requirements.txt') }}-${{ hashFiles('scripts/dev/pylint_checkers/qute_pylint/*.py') }}"
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: '3.10'
       - uses: actions/setup-node@v4
@@ -228,7 +228,7 @@ jobs:
             ~/.cache/pip
           key: "${{ matrix.testenv }}-${{ matrix.os }}-${{ matrix.python }}-${{ hashFiles('misc/requirements/requirements-*.txt') }}-${{ hashFiles('requirements.txt') }}"
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "${{ matrix.python }}"
       - name: Set up problem matchers

.github/workflows/docker.yml

@@ -19,7 +19,7 @@ jobs:
           - archlinux-webengine-qt6
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: '3.x'
       - run: pip install jinja2

.github/workflows/nightly.yml

@@ -41,7 +41,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.13"
       - name: Install dependencies

.github/workflows/recompile-requirements.yml

@@ -22,7 +22,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Set up Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: '3.9'
       - name: Recompile requirements

.github/workflows/release.yml

@@ -61,7 +61,7 @@ jobs:
           result-encoding: string
       - uses: actions/checkout@v5
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           # Doesn't really matter what we prepare the release with, but let's
           # use the same version for consistency.
@@ -140,7 +140,7 @@ jobs:
         with:
           ref: v${{ needs.prepare.outputs.version }}
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ github.event.inputs.python_version }}
       - name: Import GPG Key