Changes since v1.25.1

Breaking changes

* Change CustomMetricsAdapterServerOptions to improve options handling (https://github.com/kubernetes-sigs/custom-metrics-apiserver/pull/123, @olivierlemasle):
  * removed CustomMetricsAdapterServerOptions.Complete
  * changed CustomMetricsAdapterServerOptions.Validate from func([]string) error to func() error

Improvements

* Add qps and burst flags for the Kubernetes client (https://github.com/kubernetes-sigs/custom-metrics-apiserver/pull/121, @whitebear009)
* Add metric about metrics freshness (#126, @olivierlemasle)
* Add stylecheck linter (https://github.com/kubernetes-sigs/custom-metrics-apiserver/pull/128, @olivierlemasle)
* Add license checker (https://github.com/kubernetes-sigs/custom-metrics-apiserver/pull/129, @olivierlemasle)
* Apply Features flags including profiling and contention-profiling options (https://github.com/kubernetes-sigs/custom-metrics-apiserver/pull/130, @olivierlemasle)
* Add the option to disable APIServer's own metrics (#131, @olivierlemasle)
* Add support for OpenAPI v3 (#142, @olivierlemasle)
* Add default implementation for metrics providers (#151, @JorTurFer)
* Bump Kubernetes dependencies to v0.27.1 and Golang to 1.20 (#152, @JorTurFer)

Documentation

* Update README and mention external metrics (https://github.com/kubernetes-sigs/custom-metrics-apiserver/pull/122, @olivierlemasle)