Update setuptools to 38.5.1

[pyup-bot]

There's a new version of setuptools available.
You are currently using 38.2.4. I have updated it to 38.5.1

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

Changelog

38.5.1

---

• 1271: Revert to Cython legacy build_ext behavior for
  compatibility.

38.5.0

---

• 1229: Expand imports in build_ext to refine detection of
  Cython availability.

• 1270: When Cython is available, build_ext now uses the
  new_build_ext.

38.4.1

---

• 1257: In bdist_egg.scan_module, fix ValueError on Python 3.7.

38.4.0

---

• 1231: Removed warning when PYTHONDONTWRITEBYTECODE is enabled.

38.3.0

---

• 1210: Add support for PEP 345 Project-URL metadata.
• 1207: Add support for long_description_type to setup.cfg
  declarative config as intended and documented.

38.2.5

---

• 1232: Fix trailing slash handling in pkg_resources.ZipProvider.

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

Happy merging! 🤖

[pyup-bot]

Closing this in favor of #172