Refactor Git installation of guidata in CI workflow to use cloning instead of pip install

Author: PierreRaybaut

.github/workflows/test_pyqt5.yml

@@ -40,7 +40,10 @@ jobs:
         pip install .[test]
         if [ "${{ github.ref_name }}" = "develop" ]; then
            pip uninstall -y guidata
-           pip install git+https://github.com/PlotPyStack/guidata.git@develop
+           cd ..
+           git clone --depth 1 --branch develop https://github.com/PlotPyStack/guidata.git
+           cd PlotPy
+           pip install -e ../guidata
         fi
     - name: Lint with Ruff
       run: ruff check --output-format=github plotpy