PackDb is a simple key value messagepack store
Inspired by [kwik](https://deno.land/x/kwik/)
It uses your local storage
```rs
use pack_db::PackDb:
use serde::{Deserialize, Serialize};
struct User {
}
let store = PackDb::<User>::new(Some("data".to_owned()));
store.set("user1", User {name: "useer1", age: 16});
let user = store.get("user1");
```