add py3.12, drop py3.7, pyupgrade 3.8+ #50

Job	Run time
Validate coverage	28s
Python: 3.8-x64 on ubuntu-latest	33s
Python: 3.8-x64 on windows-latest	1m 10s
Python: 3.8-x86 on windows-latest	1m 6s
Python: 3.8-x64 on macos-latest	35s
Build the documentation	28s
Lint the package	16s
Python: 3.9-x64 on ubuntu-latest	25s
Python: 3.9-x64 on windows-latest	1m 2s
Python: 3.9-x86 on windows-latest	57s
Python: 3.9-x64 on macos-latest	45s
Python: 3.10-x64 on ubuntu-latest	29s
Python: 3.10-x64 on windows-latest	1m 25s
Python: 3.10-x86 on windows-latest	1m 27s
Python: 3.10-x64 on macos-latest	1m 11s
Python: 3.11-x64 on ubuntu-latest	33s
Python: 3.11-x64 on windows-latest	1m 31s
Python: 3.11-x86 on windows-latest	1m 37s
Python: 3.11-x64 on macos-latest	33s
Python: 3.12-x64 on ubuntu-latest	30s
Python: 3.12-x64 on windows-latest	1m 29s
Python: 3.12-x86 on windows-latest	1m 21s
Python: 3.12-x64 on macos-latest	37s
Python: pypy-3.8-x64 on ubuntu-latest	55s
Python: pypy-3.8-x64 on macos-latest	48s
	22m 11s

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