feat: Implement getUser graphQL query test

packages/backend/test/setup/global-hooks.ts

@@ -1,4 +1,4 @@
-import { transaction, Model } from 'objection';
+import { Model } from 'objection';
 import { client as knex } from '../../src/config/database';
 import logger from '../../src/helpers/logger';
 
@@ -12,7 +12,7 @@ global.beforeEach(async () => {
   // It's assigned as global.knex for the convenience even though
   // it's a transaction. It's rolled back after each test.
   // by assigning to knex, we can use it as knex.table('example') in tests files.
-  global.knex = await transaction.start(knex);
+  global.knex = await knex.transaction();
   Model.knex(global.knex);
 });