update github workflow to use env.sha and image_repo context

Author: leighmcculloch

.github/workflows/newbuild.yml

@@ -451,9 +451,8 @@ jobs:
           github.rest.repos.createCommitStatus({
             owner: context.repo.owner,
             repo: context.repo.repo,
-            sha: '${{ env.HEAD_SHA }}',
+            sha: '${{ env.sha }}',
             state: 'success',
-            context: `${{ env.IMAGE }}`,
-            target_url: '${{ env.IMAGE_URL }}',
+            context: `${{ env.image_repo }}:${{ steps.tag.outputs.tag }}`,
             description: 'Available',
           });