workflows: publish images on tags rather than on releases

This would avoid the draft release issue of triggering image building twice

.github/workflows/atlantis-image.yml

@@ -3,10 +3,9 @@ name: atlantis-image
 on:
   push:
     branches:
-      - "master"
-  release:
-    types:
-      - "published"
+      - 'master'
+    tags:
+      - 'v*.*.*'
   workflow_dispatch:
 
 jobs:
@@ -47,10 +46,10 @@ jobs:
 
     # Publish release to container registry
     - name: populate release version
-      if: ${{ github.event_name == 'release'}}
+      if: ${{ github.event_name == 'push' && startsWith(github.ref, 'refs/tags/') }}
       run: echo "RELEASE_VERSION=${GITHUB_REF#refs/*/}" >> $GITHUB_ENV
     - name: Build and push atlantis:${{ env.RELEASE_VERSION }} image
-      if: ${{ github.event_name == 'release'}}
+      if: ${{ github.event_name == 'push' && startsWith(github.ref, 'refs/tags/') }}
       uses: docker/build-push-action@v2
       with:
         context: .