Update test dependencies to more secure versions (fixes #2)
diff --git a/pom.xml b/pom.xml
index b72b943..dc82503 100644
--- a/pom.xml
+++ b/pom.xml
@@ -137,7 +137,7 @@
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
-      <version>4.11</version>
+      <version>4.13.1</version>
       <scope>test</scope>
     </dependency>
   </dependencies>