`asdf.util.filepath_to_url` does not accept `Path` instances

[Brett Graham]

Description of the problem

asdf.util.filepath_to_url raises an exception when provided with a pathlib.Path instance.

Example of the problem

import asdf, pathlib

p = pathlib.Path('foo')
asdf.util.filepath_to_url(p)  # raises TypeError: quote_from_bytes() expected bytes

System information

asdf version: main
python version: 3.10
operating system: mac osx