Bump go-plugin-api from 21.3.0 to 21.4.0
Bump go-plugin-api from 21.3.0 to 21.4.0

Bumps [go-plugin-api](https://github.com/gocd/gocd) from 21.3.0 to 21.4.0.
- [Release notes](https://github.com/gocd/gocd/releases)
- [Commits](https://github.com/gocd/gocd/compare/21.3.0...21.4.0)

---
updated-dependencies:
- dependency-name: cd.go.plugin:go-plugin-api
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
srinivasupadhya/script-executor-task,srinivasupadhya/script-executor-task,gocd-contrib/script-executor-task,gocd-contrib/script-executor-task