no_std support (#225)

* No std implementation

* Run tests with std

* Adding wasm32-unknown-unknown target

Co-authored-by: Kevin Lewi <[email protected]>

src/key_exchange/traits.rs

@@ -10,6 +10,7 @@ use crate::{
     hash::Hash,
     keypair::{PrivateKey, PublicKey, SecretKey},
 };
+use alloc::vec::Vec;
 use rand::{CryptoRng, RngCore};
 use zeroize::Zeroize;