Update matplotlib to 3.2.1

[pyup-bot]

This PR updates matplotlib from 3.1.0 to 3.2.1.

Changelog

3.2.1

This is the first bugfix release of the 3.2.x series.

This release contains several critical bug-fixes:

- fix `Quiver.set_UVC` calls with scalar inputs
- fix `bezier.get_parallels` failure from floating point rounding errors
- fix markers specified as tuples (polygons, stars, or asterisks)
- fix saving PNGs to file objects in some places
- fix saving figures using the nbAgg/notebook backend
- fix saving with tight layout using the PGF backend
- fix setting custom datapath in rcParams (note: it is still deprecated)
- fix various issues running setup.py in non-CI environments
- fix xpdf distiller
- various minor bug and documentation fixes

3.2.0rc1

This is the first release candidate from Matplotlib 3.2

3.1.1

The first bug-fix release of the 3.1 series

* Locator.nonsingular return order API change

Lots of backports of various bug fixes.

Links

• PyPI: https://pypi.org/project/matplotlib
• Changelog: https://pyup.io/changelogs/matplotlib/
• Homepage: https://matplotlib.org

[pyup-bot]

Closing this in favor of #129