clippy: remove unnecessary clones

and from::<T>(T)

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

src/server/email_notifications.rs

@@ -403,7 +403,7 @@ fn lookup_user_email(userid: &Userid) -> Option<String> {
 
     if let Ok(user_config) = user::cached_config() {
         if let Ok(user) = user_config.lookup::<User>("user", userid.as_str()) {
-            return user.email.clone();
+            return user.email;
         }
     }