Merge pull request #21 from remarkablemark/ci/codecov

ci(root): add Codecov to workflow `build.yml`

Author: remarkablemark

.github/workflows/build.yml

@@ -47,3 +47,6 @@ jobs:
 
       - name: Run test
         run: npm test
+
+      - name: Codecov
+        uses: codecov/codecov-action@v2