fix: Network Prefabs List wasn't persisting changes made in the editor. [MTT-5458] (#2410)

fix: Network Prefabs List wasn't persisting changes made in the editor.

Author: ShadauxCat

com.unity.netcode.gameobjects/Editor/Configuration/NetworkPrefabsEditor.cs

@@ -90,6 +90,8 @@ public override void OnInspectorGUI()
             }
 
             m_NetworkPrefabsList.DoLayoutList();
+
+            serializedObject.ApplyModifiedProperties();
         }
     }
 }