Update build-push-image.yml

Author: eculler

.github/workflows/build-push-image.yml

@@ -10,8 +10,6 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
-        with:
-          ref: upgrade-to-3.9
 
       - name: Login to DockerHub
         uses: docker/login-action@v1