fix: install pytest

.github/workflows/dev-build.yml

@@ -25,7 +25,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install flake8
+        pip install flake8 pytest
     - name: Analysing the code with pylint
       run: |
         flake8 --ignore E501,W503 $(git ls-files '*.py')