Bump groovy-maven-plugin from 2.0 to 2.1.1

diff --git a/pom.xml b/pom.xml
index 8bef724..36b56ea 100644
--- a/pom.xml
+++ b/pom.xml
@@ -489,7 +489,7 @@
       <plugin>
         <groupId>org.codehaus.gmaven</groupId>
         <artifactId>groovy-maven-plugin</artifactId>
-        <version>2.0</version>
+        <version>2.1.1</version>
         <executions>
           <execution>
             <id>patch-changes-xsd</id>