Remove also PR tags (as we don't push from PR)

Author: MattBlack85

.github/workflows/buildx.yml

@@ -64,7 +64,6 @@ jobs:
           tags: |
             type=raw,value=latest,enable={{is_default_branch}}
             type=ref,event=tag
-            type=ref,event=pr
 
       - name: Build (and push when not a PR)
         id: buildx