Fix Linux support

  missing dependency for EditorApplication.applicationPath

Assets/LDtkUnity/Editor/Utility/LDtkTilesetExporterUtility.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Diagnostics;
 using System.IO;
+using UnityEditor;
 using UnityEngine;
 using Debug = UnityEngine.Debug;
 
@@ -117,4 +118,4 @@ public static bool GetAppUpToDate(out Version version, out Version requiredVersi
             return version == requiredVersion;
         }
     }
-}
+}