Use latest version of rat and rat-plugin

In Gradle builds, this will still use rat 0.15.0, though
as the plugin hardcodes the version of rat that is used.

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1915481 13f79535-47bb-0310-9956-ffa450edef68

build.gradle

@@ -32,7 +32,7 @@ buildscript {
 plugins {
     id 'base'
     id 'com.dorongold.task-tree' version '2.1.1'
-    id 'org.nosphere.apache.rat' version '0.8.0'
+    id 'org.nosphere.apache.rat' version '0.8.1'
     id 'distribution'
     id "com.github.spotbugs" version '5.2.1'
     id 'de.thetaphi.forbiddenapis' version '3.6'

build.xml

@@ -349,7 +349,7 @@ under the License.
     <dependency prefix="asm-tree" artifact="org.ow2.asm:asm-tree:9.5" usage="util"/>
 
     <!-- license and api checks -->
-    <dependency prefix="rat" artifact="org.apache.rat:apache-rat:0.15" usage="util"/>
+    <dependency prefix="rat" artifact="org.apache.rat:apache-rat:0.16.1" usage="util"/>
     <dependency prefix="forbidden" artifact="de.thetaphi:forbiddenapis:3.5.1" usage="util"/>
 
     <!-- See https://www.ecma-international.org/publications/standards/Ecma-376.htm -->