fix: displayName return undefined and drop displayName from user table (#505)

server/src/database/migrations/20230704123330_alter_table_user_delete_display_name/migration.sql

@@ -0,0 +1,10 @@
+/*
+  Warnings:
+
+  - You are about to drop the column `displayName` on the `users` table. All the data in the column will be lost.
+
+*/
+-- AlterTable
+ALTER TABLE "users" DROP COLUMN "displayName",
+ALTER COLUMN "firstName" DROP DEFAULT,
+ALTER COLUMN "lastName" DROP DEFAULT;