Upgrade to Apache Rat 0.10

Notably this release resolves RAT-138 which caused excessive run-times
with some inputs.  Changelog:

http://creadur.apache.org/rat/RELEASE_NOTES.txt
diff --git a/pom.xml b/pom.xml
index 40fcfdc..0c0adf6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -69,7 +69,7 @@
       <plugin>
         <groupId>org.apache.rat</groupId>
         <artifactId>apache-rat-plugin</artifactId>
-        <version>0.8</version>
+        <version>0.10</version>
         <executions>
           <execution>
             <phase>package</phase>