SNOW-27289: HTTP 504 is not retired

Author: smtakeda

compat.py

@@ -76,7 +76,7 @@
 
     BAD_REQUEST = http.client.BAD_REQUEST
     SERVICE_UNAVAILABLE = http.client.SERVICE_UNAVAILABLE
-    GATEWAY_TIMEOUT = http.client.SERVICE_UNAVAILABLE
+    GATEWAY_TIMEOUT = http.client.GATEWAY_TIMEOUT
     FORBIDDEN = http.client.FORBIDDEN
     UNAUTHORIZED = http.client.UNAUTHORIZED
     INTERNAL_SERVER_ERROR = http.client.INTERNAL_SERVER_ERROR