update dependencies (#6267)

Signed-off-by: hongming <coder.scala@gmail.com>

vendor/k8s.io/gengo/v2/README.md

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+[![GoDoc Widget]][GoDoc]  [![GoReport]][GoReportStatus]
+
+[GoDoc]: https://godoc.org/k8s.io/gengo
+[GoDoc Widget]: https://godoc.org/k8s.io/gengo?status.svg
+[GoReport]: https://goreportcard.com/badge/github.com/kubernetes/gengo
+[GoReportStatus]: https://goreportcard.com/report/github.com/kubernetes/gengo
+
+# Gengo: a framework for building simple code generators
+
+This repo is used by Kubernetes to build some codegen tooling.  It is not
+intended to be general-purpose and makes some assumptions that may not hold
+outside of Kubernetes.
+
+In the past this repo was partially supported for external use (outside of the
+Kubernetes project overall), but that is no longer true.  We may change the API
+in incompatible ways, without warning.
+
+If you are not building something that is part of Kubernetes, DO NOT DEPEND ON
+THIS REPO.
+
+## New usage within Kubernetes
+
+Gengo is a very opinionated framework.  It is primarily aimed at generating Go
+code derived from types defined in other Go code, but it is possible to use it
+for other things (e.g. proto files).  Net new tools should consider using
+`golang.org/x/tools/go/packages` directly.  Gengo can serve as an example of
+how to do that.
+
+If you still decide you want to use gengo, see the
+[simple examples](./examples) in this repo or the more extensive tools in the
+Kubernetes [code-generator](https://github.com/kubernetes/code-generator/)
+repo.
+
+## Overview
+
+Gengo is used to build tools (generally a tool is a binary).  Each tool
+describes some number of `Targets`. A target is a single output package, which
+may be the same as the inputs (if the tool generates code alongside the inputs)
+or different.  Each `Target` describes some number of `Generators`.  A
+generator is responsible for emitting a single file into the target directory.
+
+Gengo helps the tool to load and process input packages, e.g. extracting type
+information and associating comments.  Each target will be offered every known
+type, and can filter that down to the set of types it cares about.  Each
+generator will be offered the result of the target's filtering, and can filter
+the set of types further.  Finally, the generator will be called to emit code
+for all of the remaining types.
+
+The `tracer` example in this repo can be used to examine all of the hooks.
+
+## Contributing
+
+Please see [CONTRIBUTING.md](CONTRIBUTING.md) for instructions on how to contribute.