fix 'no apple music client' error

pomice/__init__.py

@@ -18,7 +18,7 @@ if not discord.version_info.major >= 2:
         "using 'pip install discord.py'"
     )
 
-__version__ = "2.0"
+__version__ = "2.0.1a"
 __title__ = "pomice"
 __author__ = "cloudwithax"
 

pomice/pool.py

@@ -120,6 +120,8 @@ class Node:
         self._spotify_client_id = spotify_client_id
         self._spotify_client_secret = spotify_client_secret
 
+        self._apple_music_client = None
+
         if self._spotify_client_id and self._spotify_client_secret:
             self._spotify_client = spotify.Client(
                 self._spotify_client_id, self._spotify_client_secret