Properly shutdown dependency injection

Author: benwoo1110

src/main/java/org/mvplugins/multiverse/netherportals/MultiverseNetherPortals.java

@@ -159,6 +159,7 @@ private void registerEvents() {
 
     @Override
     public void onDisable() {
+        shutdownDependencyInjection();
         Logging.info("- Disabled");
     }