add codecov token

Author: Chilipp

.github/workflows/python-app.yml

@@ -38,4 +38,8 @@ jobs:
     - name: Test with pytest
       run: |
         pytest --cov=autodocsumm --cov-report=xml
+    - name: Upload codecov
+      env:
+        CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+      run: |
         codecov