Update python-app.yml

typo

.github/workflows/python-app.yml

@@ -26,7 +26,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install unittest
+        pip install unitest
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
 #    - name: Lint with flake8
 #      run: |