Prep 0.3.8 release #267

Job	Run time
deny	4m 15s
clippy	11s
coverage	3m 39s
build (stable)	35s
doc	18s
build (beta)	27s
examples (stable)	18s
build (nightly-2023-04-01)	26s
formatting	53s
examples (beta)	20s
Rust 1.58.0 MSRV	2m 12s
examples (nightly-2023-04-01)	20s
Rust 1.59.0 MSRV	2m 8s
Build for a no_std target (stable)	13s
test (stable)	14s
Build for a no_std target (beta)	18s
udeps	4m 18s
test (beta)	19s
Build for a no_std target (nightly-2023-04-01)	45s
test (nightly-2023-04-01)	1m 27s
	23m 36s

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