Update Python to 3.12 and flake inputs #3937

Job	Run time
Test (shuffled order)	3m 30s
MyPy	2m 47s
Build wheel	2m 44s
Test + Coverage	4m 7s
Linter	3m 24s
Test if testdata is up to date	3m 5s
Test Typescript	2m 53s
Test Frontend	4m 31s
Backup process	3m 53s
Formatting	2m 38s
Build nix environment on MacOS	4m 56s
Install wheel with system Python	10s
	38m 38s

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