Fix Clippy warnings

plume-models/src/inbox.rs

@@ -2,7 +2,6 @@ use activitystreams::activity::{Announce, Create, Delete, Follow, Like, Undo, Up
 
 use crate::{
     comments::Comment,
-    db_conn::DbConn,
     follows, likes,
     posts::{Post, PostUpdate},
     reshares::Reshare,

plume-models/src/users.rs

@@ -169,7 +169,7 @@ impl User {
         }
 
         for comment in Comment::list_by_author(conn, self.id)? {
-            let delete_activity = comment.build_delete(&conn)?;
+            let delete_activity = comment.build_delete(conn)?;
             crate::inbox::inbox(
                 conn,
                 serde_json::to_value(&delete_activity).map_err(Error::from)?,