cleanup: turn `pathsuboption` deprecation warning into an error

We could simply drop the check, but lets raise explicit error instead of
suffering strange error in case of misuse.

mercurial/utils/urlutil.py

@@ -14,7 +14,6 b' from .. import ('
     error,
     pycompat,
     urllibcompat,
-    util,
 )
 
 from . import (
@@ -680,8 +679,7 b' def pathsuboption(option, attr, display='
     """
     if isinstance(attr, bytes):
         msg = b'pathsuboption take `str` as "attr" argument, not `bytes`'
-        util.nouideprecwarn(msg, b"6.6", stacklevel=2)
-        attr = attr.decode('ascii')
+        raise TypeError(msg)
 
     def register(func):
         _pathsuboptions[option] = (attr, func)