Merge pull request #8 from apache/dependabot/maven/extensions/groovy/org.codehaus.groovy-groovy-2.4.21

Bump groovy from 2.1.9 to 2.4.21 in /extensions/groovy
diff --git a/extensions/groovy/pom.xml b/extensions/groovy/pom.xml
index e99ddda..224bed5 100644
--- a/extensions/groovy/pom.xml
+++ b/extensions/groovy/pom.xml
@@ -31,7 +31,7 @@
         <dependency>
             <groupId>org.codehaus.groovy</groupId>
             <artifactId>groovy</artifactId>
-            <version>2.1.9</version>
+            <version>2.4.21</version>
         </dependency>
     </dependencies>
 </project>