update module-info.java

src/main/java/module-info.java

@@ -5,6 +5,7 @@ module gui {
     requires org.apache.logging.log4j;
 
     opens de.hdm_stuttgart.battlearena to javafx.fxml;
+    opens de.hdm_stuttgart.battlearena.Controller to javafx.fxml;
     exports de.hdm_stuttgart.battlearena.Main;
     exports de.hdm_stuttgart.battlearena.Controller;
 }