ci: fix uv usage to use venv instead of --system flag

setup-uv creates a venv; use `uv venv` + `uv pip install` (no --system)
and invoke binaries directly via .venv/bin/ as vtk-index does.

Author: vicentebolea

.github/workflows/ci.yml

@@ -20,21 +20,22 @@ jobs:
       - uses: actions/checkout@v4
 
       - uses: astral-sh/setup-uv@v5
-        with:
-          python-version: "3.12"
+
+      - name: Create virtualenv
+        run: uv venv
 
       - name: Install dependencies
         run: |
-          uv pip install --system \
+          uv pip install \
             "git+https://github.com/vicentebolea/vtk-knowledge" \
             "git+https://github.com/vicentebolea/vtk-validate"
-          uv pip install --system -e ".[dev]"
+          uv pip install -e ".[dev]"
 
       - name: ruff lint
-        run: ruff check src/
+        run: .venv/bin/ruff check src/
 
       - name: ruff format check
-        run: ruff format --check src/
+        run: .venv/bin/ruff format --check src/
 
   actionlint:
     runs-on: ubuntu-latest
@@ -61,24 +62,28 @@ jobs:
       - uses: actions/checkout@v4
 
       - uses: astral-sh/setup-uv@v5
-        with:
-          python-version: ${{ matrix.python-version }}
+
+      - name: Set up Python ${{ matrix.python-version }}
+        run: uv python install ${{ matrix.python-version }}
+
+      - name: Create virtualenv
+        run: uv venv --python ${{ matrix.python-version }}
 
       - name: Install dependencies
         run: |
-          uv pip install --system \
+          uv pip install \
             "git+https://github.com/vicentebolea/vtk-knowledge" \
             "git+https://github.com/vicentebolea/vtk-validate"
-          uv pip install --system -e ".[dev]"
+          uv pip install -e ".[dev]"
 
       - name: Run unit tests
-        run: pytest -m unit -v
+        run: .venv/bin/pytest -m unit -v
 
       - name: Run client tests
-        run: pytest tests/test_client_no_server.py -v
+        run: .venv/bin/pytest tests/test_client_no_server.py -v
 
       - name: Run integration tests
-        run: pytest -m integration -v
+        run: .venv/bin/pytest -m integration -v
 
   docker-deploy:
     name: Build and Push Deployment Image