Support num-bigint 0.5 #13

num-modular 0.6.5’s num-bigint feature depends on num-bigint 0.4, whose BigUint type is distinct from the one in 0.5. As a result, consumers using num-bigint 0.5 cannot use num-modular’s modular-operation implementations.

Upgrading num-modular to depend on num-bigint 0.5 would unblock consumers such as coreutils from removing their duplicate rand 0.8 dependency. num-bigint 0.5 supports rand 0.9 and 0.10 through its rand_0_9 and rand_0_10 features.

Blocking uutils/num-prime#120.