update commons-io (#13)

diff --git a/maven-plugin-testing-harness/pom.xml b/maven-plugin-testing-harness/pom.xml
index 5bfb02e..b4a6284 100644
--- a/maven-plugin-testing-harness/pom.xml
+++ b/maven-plugin-testing-harness/pom.xml
@@ -63,7 +63,7 @@
     <dependency>
       <groupId>commons-io</groupId>
       <artifactId>commons-io</artifactId>
-      <version>2.2</version>
+      <version>2.6</version>
     </dependency>
     <dependency>
       <groupId>org.codehaus.plexus</groupId>