ci: print existing candidates (#16077)

(cherry picked from commit 9e89aed)

.github/workflows/release-pypi.yml

@@ -108,6 +108,7 @@ jobs:
         branch = f"origin/builds/{os.getenv('TAG')}"
         while True:
           remote_refs = [b.name for b in repo.remote().refs]
+          print([n for n in remote_refs if "builds" in n])
           if branch in remote_refs:
             break
           time.sleep(60)