Bump mockserver-netty from 5.1.1 to 5.6.1

Change-Id: Ie8648bc2bae3ac095fa7a923d478f31dabb39ce5
diff --git a/pom.xml b/pom.xml
index ac49436..2017c4f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -86,7 +86,7 @@
     <dependency>
       <groupId>org.mock-server</groupId>
       <artifactId>mockserver-netty</artifactId>
-      <version>5.1.1</version>
+      <version>5.6.1</version>
       <scope>test</scope>
     </dependency>