Update build.yml

Author: frankzhaopeng

.github/workflows/build.yml

@@ -27,3 +27,9 @@ jobs:
         node-version: ${{ matrix.node-version }}
     - run: yarn install --frozen-lockfile
     - run: yarn build
+    - run: yarn test:cov
+    
+    - name: Coveralls
+      uses: coverallsapp/github-action@master
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}