fix: install pytest in CI pylint workflow to resolve E0401 errors

Author: ohAnd

.github/workflows/pylint.yaml

@@ -20,7 +20,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install pylint astroid
+          pip install pylint astroid pytest
           pip install -r requirements.txt
           sudo apt-get update && sudo apt-get install -y bc  # Install bc
       - name: Analysing the code with pylint