Bump mypy, fix tests #679

Job	Run time
Build docs & run doctests	41s
Check types using pyright	36s
Verify dev env (ubuntu-latest)	22s
Tests & Mypy on 3.7	53s
Verify dev env (windows-latest)	1m 11s
Tests & Mypy on 3.8	1m 24s
Tests & Mypy on 3.9	1m 24s
Tests & Mypy on 3.10	1m 34s
Tests & Mypy on 3.11	1m 45s
Tests & Mypy on 3.12	1m 41s
Tests & Mypy on pypy-3.8	1m 6s
Tests & Mypy on pypy-3.9	1m 12s
Tests & Mypy on pypy-3.10	1m 43s
Combine & check coverage.	15s
required-checks-pass	3s
	15m 50s

Provide feedback