CI: use uv (to verify lock file), use preinstalled Python

Author: mgeier

.github/workflows/test.yml

@@ -1,6 +1,7 @@
 name: Run Tests
 on: [push, pull_request]
 env:
+  UV_PYTHON_DOWNLOADS: never
   PYTEST_ADDOPTS: "--color=yes"
 jobs:
   tests:
@@ -41,34 +42,26 @@ jobs:
       shell: bash
       run: |
         jackd --no-realtime -d dummy &
-    - name: Set up Python
-      uses: actions/setup-python@v5
-      with:
-        python-version: "3"
-    - name: Double-check Python version
-      run: |
-        python --version
+
     - uses: actions/checkout@v5
+    - name: Install uv
+      uses: astral-sh/setup-uv@v6
     - name: Install Python package
       run: |
-        python -m pip install --group test .
+        uv sync --locked
     - name: Run tests
       run: |
-        python -m pytest
+        uv run pytest
 
   docs:
     runs-on: ubuntu-latest
     steps:
-    - name: Set up Python
-      uses: actions/setup-python@v5
+    - uses: actions/checkout@v5
       with:
-        python-version: "3"
+        fetch-depth: 0
     - name: Double-check Python version
       run: |
         python --version
-    - uses: actions/checkout@v5
-      with:
-        fetch-depth: 0
     - name: Install doc dependencies
       run: |
         python -m pip install --group doc