Log Message:
py-markups: update to 3.1.0

Version 3.1.0, 2021-01-31
=========================

Incompatible changes:

* Python versions older than 3.6 are no longer supported.

Other changes:

* Instead of ``pkg_resources``, ``importlib.metadata`` is now used.
* For Markdown markup, ``markdown-extensions.yaml`` files are now supported
  in addition to ``markdown-extensions.txt`` files.
* Type annotations were added for public API.
* The reStructuredText markup no longer raises exceptions for invalid markup.
* MathJax v3 is now supported in addition to v2. Also, the Arch Linux mathjax
  packages are now supported (issue #4).
* Added Pygments CSS support for the ``pymdownx.highlight`` Markdown extension.