Add coveralls actions to workflow

.github/workflows/build.yml

@@ -55,6 +55,9 @@ jobs:
         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
 
     - name: Run tests
-      run: |
         pytest --verbose
-        pytest --cov=cast tests/
+        coverage run --source cast pytest tests/
+    - name: Coveralls GitHub Action
+      uses: coverallsapp/[email protected]
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}