feat: add BSC support #65

Job	Run time
check no-default-features	57s
check serde	56s
check std	56s
clippy / optimism	1m 56s
clippy / bsc	1m 57s
docs / optimism	1m 32s
fmt	5s
docs / bsc	1m 44s
test stable --no-default-features	59s
test stable	1m 1s
test stable --features bsc	1m 18s
test stable --features optimism,opbnb	1m 22s
test beta --no-default-features	57s
test beta	49s
test beta --features bsc	54s
test beta --features optimism,opbnb	59s
test nightly --no-default-features	48s
test nightly	1m 15s
test nightly --features bsc	1m 0s
test nightly --features optimism,opbnb	1m 12s
	22m 37s

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