Create GitHub action to analyze code with mypy

Author: everlyy

.github/workflows/mypy.yml

@@ -14,10 +14,10 @@ jobs:
       uses: actions/setup-python@v3
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
+    - name: Set up environment
       run: |
-        python -m pip install --upgrade pip
-        pip install mypy
+        bash venv.sh
     - name: Analysing the code with mypy
       run: |
+        . .venv/bin/activate
         mypy bot/TypoBot.py