Bump groovy from 2.1.9 to 2.4.21 in /extensions/groovy

Bumps [groovy](https://github.com/apache/groovy) from 2.1.9 to 2.4.21.
- [Release notes](https://github.com/apache/groovy/releases)
- [Commits](https://github.com/apache/groovy/commits)

---
updated-dependencies:
- dependency-name: org.codehaus.groovy:groovy
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
1 file changed