Update Python to 3.12 and flake inputs #3930

Job	Run time
Formatting	23m 17s
Linter	22m 47s
Backup process	23m 34s
Build wheel	2m 42s
Build nix environment on MacOS	22m 17s
Test + Coverage	22m 2s
MyPy	22m 18s
Test Frontend	22m 1s
Test (shuffled order)	21m 51s
Test if testdata is up to date	21m 42s
Test Typescript	20m 11s
Install wheel with system Python	1s
	3h 44m 43s

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