Updating `.readthedocs.yml` with Python3.11 #347

Job	Run time
Code style checks	41s
(Allowed Failure) Python 3.11 with dev version of key dependencies	1m 7s
Python 3.8 with minimal dependencies	3m 20s
Python 3.9 with all optional dependencies	3m 22s
Python 3.10 with numpy 1.23 and full coverage	3m 38s
Python 3.10 with all optional dependencies (MacOS X)	4m 10s
	16m 18s

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