Add workflow for pr checks.

.github/workflows/prchecks.yml

@@ -0,0 +1,31 @@
+name: Run tests
+
+on:  
+  push:
+  pull_request:
+    branches:
+      - master
+jobs:  
+  test:
+    runs-on: ubuntu-latest
+    permissions: 
+      contents: read
+      packages: write 
+    steps:
+      - uses: actions/setup-node@v2
+          with:
+            node-version: '12.x'
+            registry-url: 'https://registry.npmjs.org'
+      - name: Install
+        run: npm install
+      - name: Test
+        run: npm run test
+      - uses: codecov/codecov-action@v2
+        with:
+          files: coverage/*.json
+          flags: unittests
+          name: react-carousel-codecov
+          fail_ci_if_error: true
+          verbose: true 
+      - name: Build
+        run: npm run build