feat: derive proptest arbitrary for `Request` #2325

Job	Run time
wasm-wasi	1m 6s
test ubuntu-latest stable --no-default-features	1m 27s
test ubuntu-latest stable	1m 32s
docs	59s
doctest	1m 20s
test ubuntu-latest nightly --no-default-features	1m 13s
clippy	38s
test ubuntu-latest nightly	1m 22s
feature-checks	6m 21s
fmt	10s
test ubuntu-latest 1.76 --no-default-features	35s
no-std	28s
test ubuntu-latest 1.76	1m 12s
wasm-unknown	52s
test windows-latest stable --no-default-features	5m 58s
cfg-check	25s
test windows-latest stable	5m 57s
test windows-latest nightly --no-default-features	2m 43s
test windows-latest nightly	3m 47s
test windows-latest 1.76 --no-default-features	3m 22s
test windows-latest 1.76	3m 12s
test ubuntu-latest stable --all-features	2m 15s
test ubuntu-latest nightly --all-features	2m 6s
	49m 0s

Provide feedback