Remove walrus operator in case we have previous Python 3.8 for verifi…

…cations

Co-authored-by: Sutou Kouhei <kou@cozmixng.org>

dev/release/download_rc_binaries.py

@@ -124,7 +124,8 @@ def _download_url(self, url, dest_path, *, extra_args=None):
         # Retry subprocess in case it fails with OpenSSL Connection errors
         # https://issues.apache.org/jira/browse/INFRA-25274
         for attempt in range(5):
-            if delay := attempt * 3:
+            if attempt > 0:
+                delay = attempt * 3:
                 print(f"Waiting {delay} seconds before retrying {url}")
                 time.sleep(delay)
             proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,