Update pathlib2 to 2.3.0

[pyup-bot]

There's a new version of pathlib2 available.
You are currently using 2.1.0. I have updated it to 2.3.0

These links might come in handy: PyPI | Changelog | Homepage

Changelog

2.3.0

^^^^^^^^^^^^^

• Sync with upstream pathlib from CPython 3.6.1 (7d1017d).

2.2.1

^^^^^^^^^^^^^

• Fix conditional scandir dependency in wheel (reported by AvdN, see
  issue 20 and pull request 21).

2.2.0

^^^^^^^^^^^^^

• Sync with upstream pathlib from CPython 3.5.2 and 3.6.0: fix various
  exceptions, empty glob pattern, scandir, fspath.

• Support unicode strings to be used to construct paths in Python 2
  (reported by native-api, see issue 13 and pull request 15).

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖