fix MutableMapping import for py 3.8 compatibility

src/bepasty/storage/filesystem/__init__.py

@@ -1,9 +1,10 @@
-import collections
 import os
 import pickle
 import logging
 import tempfile
 
+from ...utils._compat import MutableMapping
+
 logger = logging.getLogger(__name__)
 
 
@@ -122,7 +123,7 @@ class Data(object):
         return self._file.write(data)
 
 
-class Meta(collections.MutableMapping):
+class Meta(MutableMapping):
     """
     Meta-data of item.
     """

src/bepasty/utils/_compat.py

@@ -14,9 +14,11 @@ if PY2:
     range_type = xrange  # noqa: F821
     bytes_type = str
     iteritems = lambda d: d.iteritems()  # noqa: E731
+    from collections import MutableMapping  # noqa: F401
 else:
     from urllib.parse import urlparse, urljoin
 
     range_type = range
     bytes_type = bytes
     iteritems = lambda d: iter(d.items())  # noqa: E731
+    from collections.abc import MutableMapping  # noqa: F401