Bump groovy-all to 2.4.21

This is the version that Jenkins ships, as of 2.346.3.

Author: nre-ableton

build.gradle

@@ -21,7 +21,7 @@ sourceCompatibility = 11
 targetCompatibility = 11
 
 dependencies {
-    implementation('org.codehaus.groovy:groovy-all:2.4.14')
+    implementation('org.codehaus.groovy:groovy-all:2.4.21')
     implementation('com.cloudbees:groovy-cps:1.31')
     implementation('commons-io:commons-io:2.11.0')
     implementation('org.apache.ivy:ivy:2.5.1')