ci: don't install in editable mode

.github/workflows/check.yml

@@ -38,7 +38,7 @@ jobs:
         python -m pip install --upgrade pip wheel
         python -m pip install coverage flake8 pytest pytest-qt
         # install dependencies
-        pip install -e .
+        pip install .
         # show installed packages
         pip freeze
     - name: Start application and print version