Add Python 3.13 to CI #846

Job	Run time
Build docs & run doctests	32s
Check types using pyright	27s
Verify dev env (ubuntu-latest)	24s
Verify dev env (windows-latest)	1m 10s
Tests & Mypy on 3.7	44s
Tests & Mypy on 3.8	1m 10s
Tests & Mypy on 3.9	1m 11s
Tests & Mypy on 3.10	1m 25s
Tests & Mypy on 3.11	1m 7s
Tests & Mypy on 3.12	1m 33s
Tests & Mypy on 3.13	2m 50s
Tests & Mypy on pypy-3.8	57s
Tests & Mypy on pypy-3.9	51s
Tests & Mypy on pypy-3.10	51s
Combine & check coverage.	9s
required-checks-pass	9s
	15m 30s

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