Update endpoints model

Author: AWS SDK for Go v2 automation user

codegen/smithy-aws-go-codegen/src/main/resources/software/amazon/smithy/aws/go/codegen/endpoints.json

@@ -3395,6 +3395,7 @@
       },
       "cassandra" : {
         "endpoints" : {
+          "af-south-1" : { },
           "ap-east-1" : { },
           "ap-northeast-1" : { },
           "ap-northeast-2" : { },