Support buf build deps

In the example code of `protoc-gen-openapi`, I see that `option (openapi.v3.documentation)` is already supported, but when using it in the proto file of other projects, the user needs to manually introduce `import "openapiv3/annotations.proto";` associated [annotations.proto](https://github.com/google/gnostic/blob/549bfe03567bc91a7a3033be7bb245339e73b99e/openapiv3/annotations.proto ) file to be able to compile successfully. Can you consider uploading it to [buf.build](https://buf.build), similar to https://buf.build/googleapis/googleapis, to make it easier for other users to introduce dependencies for use, thanks to this great project.

```yaml
#buf.yaml

version: v1
deps:
- buf.build/googleapis/googleapis
lint:
use:
- DEFAULT
breaking:
use:
- FILE

```