Tests

feat: implement precompile contract for opBNB #19

Job	Run time
check serde	54s
check no-default-features	53s
test stable --no-default-features	1m 12s
test stable	1m 7s
check std	50s
test stable --all-features	1m 38s
clippy	1m 12s
docs	1m 26s
test beta --no-default-features	1m 4s
test beta	59s
fmt	12s
test beta --all-features	1m 33s
test nightly --no-default-features	1m 4s
test nightly	56s
test nightly --all-features	1m 30s
	16m 30s

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