KNOX-2414 - Upgrade dom4j to 2.1.3

Signed-off-by: Kevin Risden <krisden@apache.org>
diff --git a/pom.xml b/pom.xml
index 502be7c..45cdb18 100644
--- a/pom.xml
+++ b/pom.xml
@@ -184,7 +184,7 @@
         <dependency-check-maven.version>5.3.2</dependency-check-maven.version>
         <derby.db.version>10.14.2.0</derby.db.version> <!-- 10.15.1.3 requires Java 9 -->
         <dockerfile-maven-plugin.version>1.4.13</dockerfile-maven-plugin.version>
-        <dom4j.version>2.1.1</dom4j.version>
+        <dom4j.version>2.1.3</dom4j.version>
         <easymock.version>4.2</easymock.version>
         <eclipselink.version>2.7.6</eclipselink.version>
         <ehcache.version>2.6.11</ehcache.version>