Update ms.py

ms.py

@@ -28,10 +28,13 @@ def download(filename, url):
 
 apkname = "MuseScore.AppImage"
 extra_dir = "squashfs-root"
-download(
-    filename=apkname,
-    url="https://www.modelscope.cn/studio/Genius-Society/piano_trans/resolve/master/MuseScore.AppImage",
-)
+
+if not os.path.exists(apkname):
+    download(
+        filename=apkname,
+        url="https://www.modelscope.cn/studio/Genius-Society/piano_trans/resolve/master/MuseScore.AppImage",
+    )
+    
 if not os.path.exists(extra_dir):
     subprocess.run(["chmod", "+x", f"./{apkname}"])
     subprocess.run([f"./{apkname}", "--appimage-extract"])