test: derive serde for test #5788

Job	Run time
docs	57s
check no_std	29s
clippy	45s
doctest	1m 10s
feature-checks	3m 49s
fmt	11s
wasm-unknown	1m 6s
test ubuntu-latest stable --no-default-features	1m 45s
wasm-wasi	1m 27s
test ubuntu-latest stable	1m 34s
test ubuntu-latest stable --all-features	2m 42s
test ubuntu-latest nightly --no-default-features	1m 7s
test ubuntu-latest nightly	1m 23s
test ubuntu-latest nightly --all-features	2m 2s
test ubuntu-latest 1.81 --no-default-features	57s
test ubuntu-latest 1.81	1m 1s
test windows-latest stable --no-default-features	3m 45s
test windows-latest stable	3m 37s
test windows-latest stable --all-features	5m 3s
test windows-latest nightly --no-default-features	2m 57s
test windows-latest nightly	3m 56s
test windows-latest nightly --all-features	5m 36s
test windows-latest 1.81 --no-default-features	1m 44s
test windows-latest 1.81	2m 5s
deny / cargo deny check	18s
ci success	2s
	51m 28s

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