fix: add --system flag to uv pip install in CI

Author: mariuspruvot

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
         run: uv python install ${{ matrix.python-version }}
 
       - name: Install dependencies
-        run: uv pip install -e ".[dev]"
+        run: uv pip install --system -e ".[dev]"
 
       - name: Run type checking
         run: uv run poe type