Update Invalid Swagger URL (#35595)

Author: xingsy97

sdk/webpubsub/azure-messaging-webpubsubservice/swagger/README.md

@@ -20,7 +20,7 @@ autorest
 ### Settings
 
 ```yaml
-input-file: https://raw.githubusercontent.com/Azure/azure-rest-api-specs/1735a92bdc79b446385a36ba063ea5235680709f/specification/webpubsub/data-plane/WebPubSub/stable/2022-11-01/webpubsub.json
+input-file: https://raw.githubusercontent.com/Azure/azure-rest-api-specs/main/specification/webpubsub/data-plane/WebPubSub/stable/2022-11-01/webpubsub.json
 output-folder: ../
 namespace: azure.messaging.webpubsubservice
 package-name: azure-messaging-webpubsubservice