prepare release 0.31.0 (#1197) #1655

Job	Run time
test (ubuntu-latest)	16m 6s
Build x86_64-unknown-linux-musl	10m 37s
test (macos-latest)	2m 7s
Build aarch64-unknown-linux-musl	10m 43s
test (windows-latest)	17m 58s
Build powerpc64le-unknown-linux-gnu	11m 48s
Build x86_64-apple-darwin	20m 14s
Build aarch64-apple-darwin	13m 17s
Build x86_64-pc-windows-gnu	20m 4s
Build x86_64-pc-windows-msvc	19m 47s
Post-process	7s
	2h 22m 48s

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