Use native shell commands in CI

.gitea/workflows/ci.yml

@@ -9,24 +9,23 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
-    timeout-minutes: 10
-
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        run: git checkout ${{ github.sha }}
 
       - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: '3.11'
+        run: |
+          apt-get update && apt-get install -y python3 python3-pip
 
       - name: Install dependencies
         run: |
-          python -m pip install --upgrade pip
+          python3 -m pip install --upgrade pip
           pip install -e ".[dev]"
 
       - name: Run tests
-        run: python -m pytest tests/ -v --tb=short
+        run: python3 -m pytest tests/ -v --tb=short
 
       - name: Run ruff linting
-        run: pip install ruff && ruff check src/confgen/ tests/
+        run: |
+          pip install ruff
+          ruff check src/confgen/ tests/