.github/workflows: update actions

Newer deps and uv instead of pip.

.github/workflows/python-app.yml

@@ -15,17 +15,12 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-    - name: Set up Python 3.10
-      uses: actions/setup-python@v2
+    - uses: actions/checkout@v4
+    - name: Install uv
+      uses: astral-sh/setup-uv@v5
       with:
-        python-version: '3.10'
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        pip install flake8 pytest
-        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-        if [ -f requirements-dev.txt ]; then pip install -r requirements-dev.txt; fi
+        version: 'latest'
+    - run: uv sync
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names