encoding: fix bad type annotation

This function returns utf-8 in a bytes, not a unicode.

Differential Revision: https://phab.mercurial-scm.org/D7379

mercurial/encoding.py

@@ -205,7 +205,7 b' def tolocal(s):'
 
 
 def fromlocal(s):
-    # type: (bytes) -> Text
+    # type: (bytes) -> bytes
     """
     Convert a string from the local character encoding to UTF-8