Update .github/workflows/release.yml

Change how BUILD_TIME is derived

Co-authored-by: Copilot <[email protected]>

Author: kjanat

.github/workflows/release.yml

@@ -147,7 +147,7 @@ jobs:
           annotations: ${{ steps.meta.outputs.labels }}
           build-args: |
             VERSION=${{ github.ref_name }}
-            BUILD_TIME=${{ github.event.head_commit.timestamp }}
+            BUILD_TIME=${{ github.event.head_commit.timestamp || github.event.repository.pushed_at }}
             GIT_COMMIT=${{ github.sha }}
           cache-from: type=gha
           cache-to: type=gha,mode=max