ci: fix build problems due to checkout

Sometimes, the CI check fails, for weird reasons, almost because it can't find the coverage report, apparently, it is the fault of checkout@v1. coverallsapp/github-action#55

.github/workflows/build-and-deploy.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checking out code
-        uses: actions/checkout@v1
+        uses: actions/checkout@v2
 
       - name: Configure AWS Credentials
         uses: aws-actions/configure-aws-credentials@v1