update go samples

Author: wing328

samples/client/others/go/oneof-discriminator-lookup/.openapi-generator/VERSION

@@ -1 +1 @@
-7.11.0-SNAPSHOT
+7.12.0-SNAPSHOT

samples/client/others/go/oneof-discriminator-lookup/README.md

@@ -7,7 +7,7 @@ This API client was generated by the [OpenAPI Generator](https://openapi-generat
 
 - API version: 1.0.0
 - Package version: 1.0.0
-- Generator version: 7.11.0-SNAPSHOT
+- Generator version: 7.12.0-SNAPSHOT
 - Build package: org.openapitools.codegen.languages.GoClientCodegen
 
 ## Installation