fix for online audio sources

Author: tatsumoto-ren

japanese/audio_manager/audio_source.py

@@ -58,7 +58,7 @@ def join(self, *args) -> Union[str, bytes]:
             return os.path.join(*args)
         else:
             # URLs are always joined with '/'.
-            return "/".join(*args)
+            return "/".join(args)
 
     @property
     def is_local(self) -> bool: