Prepare v0.12.1 release (#66) #341

Job	Run time
Check doc links	18s
Miri ubuntu-latest	1m 39s
Check	34s
Miri windows-latest	2m 25s
Clippy	25s
Miri macos-latest	1m 30s
Rustfmt	14s
address sanitizer	1m 6s
Test stable on ubuntu-latest	1m 46s
memory sanitizer	1m 8s
Test nightly on ubuntu-latest	1m 41s
thread sanitizer	1m 4s
Test stable on windows-latest	3m 40s
leak sanitizer	1m 3s
Test nightly on windows-latest	3m 19s
Test stable on macos-latest	2m 4s
Test nightly on macos-latest	1m 58s
	25m 54s

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