update metadata

Author: sdk-team

metadatas/vpc/AllocateIpv6InternetBandwidth.json

@@ -38,7 +38,7 @@
       "name": "Ipv6GatewayId",
       "position": "Query",
       "type": "String",
-      "required": true
+      "required": false
     },
     {
       "name": "RegionId",