build(pyproject): open repo dir before linting

.github/workflows/main.yml

@@ -49,6 +49,7 @@ jobs:
         poetry install --no-interaction
     - name: Lint with flake8
       run: |
+        cd ${GITHUB_WORKSPACE}
         # stop the build if there are Python syntax errors or undefined names
         poetry run flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
         # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide