Added xxhash 0.8.1 DUB module (D implementation)

[Paul Backus]

On Sunday, 29 May 2022 at 07:43:20 UTC, Carsten Schlote wrote:
> Source: https://gitlab.com/carsten.schlote/xxhash3
> Dub Code: https://code.dlang.org/packages/xxhash3
>
[...]
>
> Optimized code already outperforms the phobos built-in digest 
> types. See the benchmarks reported by tool at 
> https://gitlab.com/carsten.schlote/hashbench

Great work! High-quality implementations of foundational 
algorithms like these are always a welcome addition to the D 
ecosystem. :)