add pytest to sys PATH

.github/workflows/check-lint.yml

@@ -34,7 +34,6 @@ jobs:
           curl -sSL "https://install.python-poetry.org" | python -
           # Adding `poetry` to `$PATH`:
           echo "$HOME/.local/bin" >> $GITHUB_PATH
-
       - name: Set up cache
         uses: actions/cache@v3
         with:
@@ -62,10 +61,11 @@ jobs:
       #----------------------------------------------
       - name: Analysing the code with mypy
         run: |
+          source .venv/bin/activate
           poetry run mypy .
       - name: Analysing the code with flake8
         run: |
-          poetry run flake8 .
+          poetry run flake8 app
       - name: Analysing code with isort
         run: |
           poetry run isort --check-only app