use action to build Dockerfile

Author: hobu

.github/workflows/build.yml

@@ -21,7 +21,11 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
-      - name: Build
-        shell: bash -l {0}
-        run: |
-          ./build.sh
+      - name: Build and push Docker images
+        uses: docker/build-push-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+          repository: pdal/lambda
+          tag_with_ref: true
+          tag_with_sha: true