ci: disable push artifacts on fork repos

disabling push artifacts github action on the
fork repos as it doesnot makes sense to run push
actions on the fork repo.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

.github/workflows/publish-artifacts.yaml

@@ -13,6 +13,7 @@ jobs:
   push:
     name: Publish artifacts
     runs-on: ubuntu-latest
+    if: github.repository == 'ceph/ceph-csi'
     steps:
       - uses: actions/checkout@v2