Bump groovy from 2.4.20 to 2.4.21

Bumps [groovy](https://github.com/apache/groovy) from 2.4.20 to 2.4.21.
- [Release notes](https://github.com/apache/groovy/releases)
- [Commits](https://github.com/apache/groovy/commits)

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

pom.xml

@@ -70,7 +70,7 @@
     <dependency>
       <groupId>org.codehaus.groovy</groupId>
       <artifactId>groovy</artifactId>
-      <version>2.4.20</version>
+      <version>2.4.21</version>
     </dependency>
 
     <dependency>