fix: some compile time errors

Only 174 errors left!

src/database/key_value/pusher.rs

@@ -1,3 +1,7 @@
+use ruma::{UserId, api::client::push::{set_pusher, get_pushers}};
+
+use crate::{service, database::KeyValueDatabase, Error};
+
 impl service::pusher::Data for KeyValueDatabase {
     fn set_pusher(&self, sender: &UserId, pusher: set_pusher::v3::Pusher) -> Result<()> {
         let mut key = sender.as_bytes().to_vec();