Bump junit from 4.12 to 4.13.1 (#22)

Author: dependabot[bot]

pom.xml

@@ -41,7 +41,7 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>4.13.1</version>
             <optional>true</optional>
             <scope>provided</scope>
         </dependency>