Format code with yapf

This commit fixes the style issues introduced in 287fbbc according to the output
from yapf.

Details: https://deepsource.io/gh/kokarare1212/librespot-python/transform/84617c1e-f44f-4f57-8da5-04836eaee6a0/

librespot/audio/__init__.py

@@ -216,6 +216,7 @@ class AbsChunkedInputStream(io.BytesIO, HaltListener):
         return self.__decoded_length
 
     class ChunkException(IOError):
+
         @staticmethod
         def from_stream_error(stream_error: int):
             return AbsChunkedInputStream \
@@ -280,6 +281,7 @@ class AudioKeyManager(PacketsReceiver, Closeable):
         return key
 
     class Callback:
+
         def key(self, key: bytes) -> None:
             raise NotImplementedError