Updates to Edition 2021 #480

Job	Run time
clippy/stable	27s
Pass MSRV values to other jobs	2s
format/nightly	15s
nostd/thumbv6m-none-eabi/stable	20s
cargo-careful	2m 28s
docs/nightly	20s
cross_test/i686-unknown-linux-gnu/stable	2m 19s
miri	8m 41s
cross_test/s390x-unknown-linux-gnu/stable	9m 36s
tests/nightly	3m 29s
tests/beta	3m 1s
tests/stable	3m 4s
tests/1.64.0	4m 37s
blas-msrv	56s
conclusion	4s
	39m 39s

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