CI: use uv for docs

Author: mgeier

.github/workflows/docs.yml

@@ -1,32 +1,27 @@
 name: Build docs and check links
 on: [push, pull_request]
+env:
+  SPHINX: uv run --locked sphinx-build -W --keep-going --color
+  UV_PYTHON_DOWNLOADS: never
 jobs:
   docs-linkcheck:
     runs-on: ubuntu-latest
     steps:
       - name: Install pandoc
         run: |
           sudo apt-get install --no-install-recommends pandoc
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: "3.10"
-      - name: Double-check Python version
-        run: |
-          python --version
-      - name: Clone Git repository (without depth limitation)
+      - name: Install uv
+        uses: astral-sh/setup-uv@v7
+      - name: Clone Git repository (no submodules, without depth limitation)
         uses: actions/checkout@v6
         with:
           fetch-depth: 0
-      - name: Install dependencies
-        run: |
-          python -m pip install --group doc
       - name: Build HTML
         run: |
-          python -m sphinx -W --keep-going --color -d _build/doctrees/ doc/ _build/html/ -b html
+          $SPHINX -d _build/doctrees/ doc/ _build/html/ -b html
       - name: Check links
         run: |
-          python -m sphinx -W --keep-going --color -d _build/doctrees/ doc/ _build/linkcheck/ -b linkcheck
+          $SPHINX -d _build/doctrees/ doc/ _build/linkcheck/ -b linkcheck
       - name: Upload linkcheck results
         uses: actions/upload-artifact@v6
         if: ${{ success() || failure() }}