update sample

Author: yshrsmz

samples/client/petstore/kotlin-multiplatform-allOff-discriminator/.openapi-generator/VERSION

@@ -1 +1 @@
-7.15.0-SNAPSHOT
+7.16.0-SNAPSHOT

samples/client/petstore/kotlin-multiplatform-allOff-discriminator/README.md

@@ -7,7 +7,7 @@ This API client was generated by the [OpenAPI Generator](https://openapi-generat
 
 - API version: 0.1
 - Package version: 
-- Generator version: 7.15.0-SNAPSHOT
+- Generator version: 7.16.0-SNAPSHOT
 - Build package: org.openapitools.codegen.languages.KotlinClientCodegen
 For more information, please visit [https://example.org](https://example.org)