Migrate github.com/spaolacci/murmur3 to github.com/twmb/murmur3

[andrewmains12]

Switches out github.com/spaolacci/murmur3 for github.com/twmb/murmur3 as a workaround for spaolacci/murmur3#29.

Property tests suggest functional equivalence to the existing library, and the benchmarks quoted by the library maintainers suggest perf is mostly equivalent, though it does take a 30% hit for use of safe code on small byte arrays:

You will notice that at small sizes, the other library is better. This is due to this library converting to safe code for Go 1.14. At large sizes, this library is nearly identical to the other. On amd64, the 64 bit and 128 bit sums come out to ~9% faster.

32 bit sums:

32Sizes/32-12     3.00GB/s ± 1%  2.12GB/s ±11%  -29.24%  (p=0.000 n=9+10)
32Sizes/64-12     3.61GB/s ± 3%  2.79GB/s ± 8%  -22.62%  (p=0.000 n=10+10)
32Sizes/128-12    3.47GB/s ± 8%  2.79GB/s ± 4%  -19.47%  (p=0.000 n=10+10)
32Sizes/256-12    3.66GB/s ± 4%  3.25GB/s ± 6%  -11.09%  (p=0.000 n=10+10)
32Sizes/512-12    3.78GB/s ± 3%  3.54GB/s ± 4%   -6.30%  (p=0.000 n=9+9)
32Sizes/1024-12   3.86GB/s ± 3%  3.69GB/s ± 5%   -4.46%  (p=0.000 n=10+10) a 
32Sizes/2048-12   3.85GB/s ± 3%  3.81GB/s ± 3%     ~     (p=0.079 n=10+9)
32Sizes/4096-12   3.90GB/s ± 3%  3.82GB/s ± 2%   -2.14%  (p=0.029 n=10+10)
32Sizes/8192-12   3.82GB/s ± 3%  3.78GB/s ± 7%     ~     (p=0.529 n=10+10)

If desired I can bake this change in a shadow environment with reasonable traffic to vet out the performance. I'm also happy to add more M3DB specific microbenchmarks, though some guidance on what would be helpful would be appreciated. First thought is to get a sampling of ID lengths and run them through.

[vdarulis]

LGTM, the library is a fine replacement.