Update vendored beets to 1.6.0

Updates colorama to 0.4.6
Adds confuse version 1.7.0
Updates jellyfish to 0.9.0
Adds mediafile 0.10.1
Updates munkres to 1.1.4
Updates musicbrainzngs to 0.7.1
Updates mutagen to 1.46.0
Updates pyyaml to 6.0
Updates unidecode to 1.3.6

libs/common/beetsplug/fromfilename.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # This file is part of beets.
 # Copyright 2016, Jan-Erik Dahlin
 #
@@ -16,13 +15,11 @@
 """If the title is empty, try to extract track and title from the
 filename.
 """
-from __future__ import division, absolute_import, print_function
 
 from beets import plugins
 from beets.util import displayable_path
 import os
 import re
-import six
 
 
 # Filename field extraction patterns.
@@ -124,7 +121,7 @@ def apply_matches(d):
     # Apply the title and track.
     for item in d:
         if bad_title(item.title):
-            item.title = six.text_type(d[item][title_field])
+            item.title = str(d[item][title_field])
         if 'track' in d[item] and item.track == 0:
             item.track = int(d[item]['track'])
 
@@ -133,7 +130,7 @@ def apply_matches(d):
 
 class FromFilenamePlugin(plugins.BeetsPlugin):
     def __init__(self):
-        super(FromFilenamePlugin, self).__init__()
+        super().__init__()
         self.register_listener('import_task_start', filename_task)