Prepare 5.2.1 release (OpenAPITools#10161)

* prepare for 5.2.1 release

* update samples

Prepare v5.2.0 release (OpenAPITools#9920)

* 5.2.0 release

* update samples

* update meta codegen

v5.1.1 release (OpenAPITools#9421)

Prepare v5.1.0 release (OpenAPITools#9017)

* prepare v5.1.0 release

* update samples (dart-dio-next)

Prepare v5.0.1 release (OpenAPITools#8627)

* release 5.0.1

* update samples

Prepare v5.0.0 release (OpenAPITools#8247)

* update to 5.0.0

* update samples

Prepare 5.0.0 beta3 (OpenAPITools#7984)

* prepare 5.0.0-beta3 release

* update samples

* remove beta3 from readme

Prepare 5.0.0-beta2 release (OpenAPITools#7345)

* update version

* update doc

* update samples

Prepare 5.0.0-beta release (OpenAPITools#6803)

* prepare 5.0.0-beta release

* fix java-client pom

Prepare 4.3.1 release (OpenAPITools#6187)

* prepare 4.3.1 release

* update doc