fix code style

Co-authored-by: Quentin Gliech <quenting@element.io>

Author: odelcroi

crates/handlers/src/upstream_oauth2/link.rs

@@ -697,13 +697,11 @@ pub(crate) async fn post(
 
             let maybe_user = repo.user().find_by_username(&localpart.unwrap()).await?;
 
-            if maybe_user.is_none() {
-                //user can not be None at this stage
+            let Some(user) = maybe_user else {
+                // user cannot be None at this stage
                 return Err(RouteError::InvalidFormAction);
             }
 
-            let user = maybe_user.unwrap();
-
             let on_conflict = provider.claims_imports.localpart.on_conflict;
 
             match on_conflict {