rust http-server: Using u32 rather then usize

When looking at [`http-server` ](https://programming-language-benchmarks.vercel.app/problem/http-server)I believe we could have a more apples to apples comparison by using a `u32` or `u64` sense the inputs are a positive N. In other cases for signed ints `i32` or `i64` may be a better comparison.

https://github.com/hanabi1224/Programming-Language-Benchmarks/blob/d454527efb47eb3250f5fc8bb4cb9ac88eb78c67/bench/algorithm/http-server/1.rs#L76