Bump groovy from 2.5.18 to 2.5.20

Bumps [groovy](https://github.com/apache/groovy) from 2.5.18 to 2.5.20.
- [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:development
  update-type: version-update:semver-patch
...

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

pom.xml

@@ -113,7 +113,7 @@
         <!-- Test 3rd-party dependencies: -->
         <easymock.version>5.0.1</easymock.version>
         <gmaven.version>2.1.0</gmaven.version>
-        <groovy.version>2.5.18</groovy.version>
+        <groovy.version>2.5.20</groovy.version>
         <junit.version>4.13.2</junit.version>
         <junit.server.jetty.version>0.11.0</junit.server.jetty.version>
         <hibernate.version>5.6.14.Final</hibernate.version>