Adding [test] coverage action for coveralls

.github/workflows/coverage.yml

@@ -0,0 +1,23 @@
+name: test
+on:
+  push:
+    branches:
+      - coverage-action
+jobs:
+  build:
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        node-version: [14.x]
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v2
+      with:
+        node-version: ${{ matrix.node-version }}
+        cache: 'yarn'
+    - run: yarn install --frozen-lockfile
+    - run: yarn lint
+    - run: yarn test
+    - name: Coveralls
+      uses: coverallsapp/github-action@v2