Log Message:
py-cairo: update to 1.20.1.

1.20.1 - 2021-06-03
-------------------

* Use poetry for development :pr:`232`
* setup.py: Respect the PKG_CONFIG environment variable :pr:`235`
* Make import_cairo inline in addition to static :pr`224`
* docs: Fix example in Pattern.set_filter() docs _pr_`221`
* docs: Fix build with newer sphinx :pr:`222`
* docs: Fix NumPy width, height-conventions in examples :pr:`231`
* docs: Last parameter of rel_curve_to should be dy3, not dy4 :pr:`230`
* mypy: Fixes for mypy 0.800+ :pr:`233`
* mypy: Don't run mypy via pytest :pr:`234`