Only release images on submariner-io

This avoids attempting to release images from forks.

Signed-off-by: Stephen Kitt <[email protected]>

.github/workflows/release.yml

@@ -13,6 +13,7 @@ permissions: {}
 jobs:
   release:
     name: Release Images
+    if: github.repository_owner == 'submariner-io'
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repository