fix compilation error after breaking change from gotatun 0.1.2

[Max1Truc]

This PR fixes a compilation error that stems from a breaking change in gotatun 0.1.2.

When using wireguard-netstack from my code, I get this compilation error:

$ cargo new --bin testcreateforbugreport
$ cd testcreateforbugreport
$ cargo add wireguard-netstack
$ cargo build
[...]
   Compiling wireguard-netstack v0.2.0 (wireguard-hyper-connector/crates/wireguard-netstack)
error[E0308]: mismatched types
  --> crates/wireguard-netstack/src/wireguard.rs:75:13
   |
69 |         let tunn = Tunn::new(
   |                    --------- arguments to this function are incorrect
...
75 |             None,                        // No rate limiter for client
   |             ^^^^ expected `Arc<RateLimiter>`, found `Option<_>`
   |
   = note: expected struct `Arc<RateLimiter>`
                found enum `std::option::Option<_>`
note: associated function defined here
  --> ~/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/gotatun-0.1.2/src/noise/mod.rs:70:12
   |
70 |     pub fn new(
   |            ^^^

For more information about this error, try `rustc --explain E0308`.
error: could not compile `wireguard-netstack` (lib) due to 1 previous error