fix: support u64 hex from str for BlockId (#1396) #4249

Job	Run time
check no_std	43s
docs	1m 58s
clippy	1m 43s
doctest	3m 18s
cfg-check	1m 13s
feature-checks	8m 36s
fmt	11s
wasm-unknown	2m 27s
wasm-wasi	3m 54s
test ubuntu-latest stable --no-default-features	2m 43s
test ubuntu-latest stable	2m 41s
test ubuntu-latest stable --all-features	3m 10s
test ubuntu-latest nightly --no-default-features	2m 22s
test ubuntu-latest nightly	2m 32s
test ubuntu-latest nightly --all-features	2m 53s
test ubuntu-latest 1.79 --no-default-features	1m 50s
test ubuntu-latest 1.79	1m 55s
test windows-latest stable --no-default-features	7m 14s
test windows-latest stable	7m 14s
test windows-latest stable --all-features	7m 47s
test windows-latest nightly --no-default-features	6m 51s
test windows-latest nightly	5m 54s
test windows-latest nightly --all-features	6m 1s
test windows-latest 1.79 --no-default-features	3m 39s
test windows-latest 1.79	3m 17s
	1h 32m 6s

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