Pass env var correctly

Author: danielballan

.github/workflows/docker-publish.yml

@@ -88,7 +88,9 @@ jobs:
           chmod +x /usr/local/bin/canary
 
       - name: Validate container
-        run: canary validate --file canary-validator.yml ${{ env.IMAGE_NAME }}
+        run: canary validate --file canary-validator.yml $IMAGE_NAME
+        env:
+          IMAGE_NAME: ${{ env.IMAGE_NAME }}
 
       # Sign the resulting Docker image digest except on PRs.
       # This will only write to the public Rekor transparency log when the Docker