Run unit tests only on chip8 package

Author: craigthomas

.github/workflows/python-app.yml

@@ -18,6 +18,6 @@ jobs:
       run: |
         pip install -r requirements.txt
         sudo apt-get install xvfb
-        xvfb-run --auto-servernum coverage run -m unittest
+        xvfb-run --auto-servernum coverage run --source=chip8 -m unittest
     - name: Codecov
       uses: codecov/codecov-action@v1.5.2