update junit version to 4.13 (#753)

Author: ddsharpe

pom.xml

@@ -66,7 +66,7 @@
             <dependency>
                 <groupId>junit</groupId>
                 <artifactId>junit</artifactId>
-                <version>4.12</version>
+                <version>4.13.1</version>
             </dependency>
             <dependency>
                 <groupId>com.google.guava</groupId>