Update gson to 2.2.4

By: Thinkofdeath <thinkofdeath@spigotmc.org>

paper-server/pom.xml

@@ -86,7 +86,7 @@
     <dependency>
       <groupId>com.google.code.gson</groupId>
       <artifactId>gson</artifactId>
-      <version>2.1</version>
+      <version>2.2.4</version>
     </dependency>
     <dependency>
       <groupId>org.avaje</groupId>