[bug]: Update gh-pages fails

[epogrebnyak]

mudkip build --update-gh-pages fails with following trace:

Traceback (most recent call last):
  File "/opt/python/3.10.4/lib/python3.10/site-packages/mudkip/cli.py", line 22, in exception_handler
    yield
  File "/opt/python/3.10.4/lib/python3.10/site-packages/mudkip/cli.py", line 135, in build
    application.build(
  File "/opt/python/3.10.4/lib/python3.10/site-packages/mudkip/application.py", line 313, in build
    GitHubPagesUpdater(self.sphinx.outdir, self.config.repository).update()
  File "/opt/python/3.10.4/lib/python3.10/site-packages/mudkip/github.py", line 23, in update
    run(["git", "remote", "add", "origin", self.repository])
  File "/opt/python/3.10.4/lib/python3.10/subprocess.py", line 501, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/opt/python/3.10.4/lib/python3.10/subprocess.py", line 966, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/opt/python/3.10.4/lib/python3.10/subprocess.py", line 1775, in _execute_child
    self.pid = _posixsubprocess.fork_exec(
TypeError: expected str, bytes or os.PathLike object, not NoneType

[epogrebnyak]

perhaps an error with repo being renamed after creation, but ghp-import does same job without error on the same environment, +1 to use it for #204:

ghp-import -pfn docs/_build
Enumerating objects: 77, done.
Counting objects: 100% (77/77), done.
Delta compression using up to 4 threads
Compressing objects: 100% (70/70), done.
Writing objects: 100% (77/77), 3.08 MiB | 6.00 MiB/s, done.
Total 77 (delta 7), reused 0 (delta 0), pack-reused 0
remote: Resolving deltas: 100% (7/7), done.
remote: This repository moved. Please use the new location:
remote:   https://github.com/epogrebnyak/sphinx-pdf-with-mudkip.git
remote: 
remote: Create a pull request for 'gh-pages' on GitHub by visiting:
remote:      https://github.com/epogrebnyak/sphinx-pdf-with-mudkip/pull/new/gh-pages
remote: 
To https://github.com/epogrebnyak/sphinx-pdf-with-mudkit
 * [new branch]      gh-pages -> gh-pages
 *