Update endpoints model

Author: aws-sdk-swift-automation

codegen/sdk-codegen/sdk-endpoints.json

@@ -17471,6 +17471,7 @@
           "ap-southeast-3" : { },
           "ap-southeast-4" : { },
           "ap-southeast-5" : { },
+          "ap-southeast-6" : { },
           "ap-southeast-7" : { },
           "ca-central-1" : {
             "variants" : [ {