ci: use dev mode with pip

Author: machow

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          python -m pip install .[test]
+          python -m pip install -e .[test]
       - name: Run tests
         run: |
           pytest pins -m 'not fs_rsc and not skip_on_github' $PYTEST_OPTS