Merge pull request #49 from apache/dependabot/maven/html4j-maven-plugin/org.codehaus.groovy-groovy-2.4.21

Bump groovy from 1.8.3 to 2.4.21 in /html4j-maven-plugin
diff --git a/html4j-maven-plugin/pom.xml b/html4j-maven-plugin/pom.xml
index 7e39a80..87de5d0 100644
--- a/html4j-maven-plugin/pom.xml
+++ b/html4j-maven-plugin/pom.xml
@@ -129,7 +129,7 @@
       <dependency>
           <groupId>org.codehaus.groovy</groupId>
           <artifactId>groovy</artifactId>
-          <version>1.8.3</version>
+          <version>2.4.21</version>
           <scope>provided</scope>
       </dependency>
   </dependencies>