Update beets to 1.4.7

Also updates:
- colorama-0.4.1
- jellyfish-0.6.1
- munkres-1.0.12
- musicbrainzngs-0.6
- mutagen-1.41.1
- pyyaml-3.13
- six-1.12.0
- unidecode-1.0.23

libs/beetsplug/bucket.py

@@ -21,7 +21,8 @@ from __future__ import division, absolute_import, print_function
 from datetime import datetime
 import re
 import string
-from itertools import tee, izip
+from six.moves import zip
+from itertools import tee
 
 from beets import plugins, ui
 
@@ -37,7 +38,7 @@ def pairwise(iterable):
     "s -> (s0,s1), (s1,s2), (s2, s3), ..."
     a, b = tee(iterable)
     next(b, None)
-    return izip(a, b)
+    return zip(a, b)
 
 
 def span_from_str(span_str):
@@ -137,9 +138,10 @@ def str2fmt(s):
 def format_span(fmt, yearfrom, yearto, fromnchars, tonchars):
     """Return a span string representation.
     """
-    args = (bytes(yearfrom)[-fromnchars:])
+    args = (str(yearfrom)[-fromnchars:])
     if tonchars:
-        args = (bytes(yearfrom)[-fromnchars:], bytes(yearto)[-tonchars:])
+        args = (str(yearfrom)[-fromnchars:], str(yearto)[-tonchars:])
+
     return fmt % args