chore: release 0.4.0 #4269

Job	Run time
doctest	1m 2s
test ubuntu-latest stable --no-default-features	1m 14s
test ubuntu-latest stable	1m 34s
clippy	38s
check no_std	18s
test ubuntu-latest stable --all-features	2m 17s
test ubuntu-latest nightly --no-default-features	1m 7s
test ubuntu-latest nightly	1m 10s
wasm-unknown	43s
feature-checks	3m 17s
test ubuntu-latest nightly --all-features	2m 1s
test ubuntu-latest 1.79 --no-default-features	31s
wasm-wasi	1m 15s
test ubuntu-latest 1.79	44s
test windows-latest stable --no-default-features	5m 17s
cfg-check	22s
docs	58s
test windows-latest stable	4m 36s
test windows-latest stable --all-features	6m 46s
fmt	11s
test windows-latest nightly --no-default-features	4m 2s
test windows-latest nightly	2m 59s
test windows-latest nightly --all-features	5m 45s
test windows-latest 1.79 --no-default-features	3m 14s
test windows-latest 1.79	2m 35s
	54m 36s

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