update test dependencies
diff --git a/pom.xml b/pom.xml
index 1b10f35..00e017b 100644
--- a/pom.xml
+++ b/pom.xml
@@ -79,13 +79,13 @@
     <dependency>

       <groupId>junit</groupId>

       <artifactId>junit</artifactId>

-      <version>4.11</version>

+      <version>4.13</version>

       <scope>test</scope>

     </dependency>

     <dependency>

       <groupId>org.mockito</groupId>

       <artifactId>mockito-core</artifactId>

-      <version>1.9.5</version>

+      <version>2.28.2</version>

       <scope>test</scope>

     </dependency>

   </dependencies>