Add support for Python 3.10 and 3.11

[hugovk]

Python 3.11 was released on 2022-10-24 🚀

---

Also maybe time to drop EOL Python <= 3.6?

Here's the pip installs for ptyprocess from PyPI for October 2022:

category	percent	downloads
3.7	29.33%	7,840,362
3.8	23.53%	6,289,131
3.9	18.12%	4,843,521
3.10	12.51%	3,344,769
3.6	7.83%	2,092,917
null	6.31%	1,687,690
2.7	1.73%	462,046
3.11	0.42%	111,185
3.5	0.17%	45,885
3.4	0.05%	13,545
3.12	0.00%	143
3.3	0.00%	69
3.2	0.00%	6
Total		26,731,269

Source: pip install -U pypistats && pypistats python_minor ptyprocess --last-month

[hugovk]

The second and final Python 3.12 release candidate is out! 🚀

Call to action

We strongly encourage maintainers of third-party Python projects to prepare their projects for 3.12 compatibilities during this phase, and where necessary publish Python 3.12 wheels on PyPI to be ready for the final release of 3.12.0.

See also https://dev.to/hugovk/help-test-python-312-beta-1508/