docs: Add migration guide #72

Job	Run time
MSRV	27s
Build on wasm32-unknown-unknown	35s
Verify commit messages	39s
Test on ubuntu-22.04	1m 23s
Test on macos-12	2m 13s
Clippy	34s
Test on windows-2022	3m 50s
Run test coverage	1m 14s
Rustfmt	12s
Python lints	16s
Check features	54s
Python 3.8 on ubuntu-22.04	1m 50s
Fuzzing builder	3m 39s
Python 3.9 on ubuntu-22.04	1m 50s
Fuzzing validation	3m 43s
Python 3.10 on ubuntu-22.04	1m 55s
Python 3.11 on ubuntu-22.04	1m 45s
Python 3.12 on ubuntu-22.04	1m 55s
Python 3.8 on macos-12	5m 18s
Python 3.9 on macos-12	3m 59s
Python 3.10 on macos-12	3m 46s
Python 3.11 on macos-12	5m 10s
Python 3.12 on macos-12	5m 57s
Python 3.8 on windows-2022	8m 26s
Python 3.9 on windows-2022	5m 18s
Python 3.10 on windows-2022	6m 20s
Python 3.11 on windows-2022	4m 29s
Python 3.12 on windows-2022	5m 55s
	1h 23m 32s

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