chore: improve FromStr for `BlockNumberOrTag` to be case-insensitive … #5699

Job	Run time
doctest	2m 2s
wasm-unknown	1m 3s
clippy	53s
docs	2m 9s
check no_std	23s
feature-checks	4m 17s
wasm-wasi	1m 38s
test ubuntu-latest stable --no-default-features	1m 56s
test ubuntu-latest stable	1m 49s
fmt	10s
test ubuntu-latest stable --all-features	2m 35s
test ubuntu-latest nightly --no-default-features	2m 38s
test ubuntu-latest nightly	2m 40s
test ubuntu-latest nightly --all-features	3m 5s
test ubuntu-latest 1.81 --no-default-features	1m 2s
test ubuntu-latest 1.81	1m 5s
test windows-latest stable --no-default-features	6m 7s
test windows-latest stable	4m 54s
test windows-latest stable --all-features	5m 50s
test windows-latest nightly --no-default-features	6m 16s
test windows-latest nightly	5m 46s
test windows-latest nightly --all-features	7m 11s
test windows-latest 1.81 --no-default-features	2m 28s
deny / cargo deny check	23s
test windows-latest 1.81	2m 44s
ci success	4s
	1h 11m 8s

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