chore: release 0.12.0 #822

Job	Run time
doctest	1m 8s
feature-checks	2m 56s
docs	25s
clippy	47s
fmt	15s
test stable (ubuntu-latest)	1m 3s
test stable --all-features (ubuntu-latest)	2m 8s
test 1.70 (ubuntu-latest)	38s
test stable (macos-latest)	1m 25s
test stable --all-features (macos-latest)	2m 28s
test 1.70 (macos-latest)	49s
test stable (windows-latest)	4m 26s
test stable --all-features (windows-latest)	5m 5s
test 1.70 (windows-latest)	2m 3s
	25m 36s

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