make set avatar, displayname, and blurhash async and forgot another let _

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/service/admin/mod.rs

@@ -600,7 +600,8 @@ impl Service {
 
                     services()
                         .users
-                        .set_displayname(&user_id, Some(displayname))?;
+                        .set_displayname(&user_id, Some(displayname))
+                        .await?;
 
                     // Initial account data
                     services().account_data.update(