rpc: derive arbitrary for `TransactionRequest` #3373

Job	Run time
doctest	2m 17s
test ubuntu-latest stable --no-default-features	2m 24s
test ubuntu-latest stable	2m 27s
clippy	1m 15s
test ubuntu-latest nightly --no-default-features	1m 19s
test ubuntu-latest nightly	1m 19s
feature-checks	5m 38s
no-std	28s
test ubuntu-latest 1.76 --no-default-features	1m 19s
test ubuntu-latest 1.76	1m 26s
test windows-latest stable --no-default-features	6m 30s
wasm-unknown	1m 15s
wasm-wasi	2m 5s
test windows-latest stable	9m 39s
test windows-latest nightly --no-default-features	4m 46s
cfg-check	28s
test windows-latest nightly	4m 29s
test windows-latest 1.76 --no-default-features	3m 49s
docs	57s
test windows-latest 1.76	3m 15s
fmt	11s
	57m 16s

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