fix(tests): cast onboardingState to jsonb in migration test

- Updated the SQL query in the onboarding migration test to explicitly cast the onboardingState to jsonb, ensuring proper data type handling during the update process.

Author: mantrakp04

apps/backend/prisma/migrations/20260420000000_add_project_onboarding_state/tests/default-and-updates.ts

@@ -29,7 +29,7 @@ export const postMigration = async (sql: Sql, ctx: Awaited<ReturnType<typeof pre
   };
   await sql`
     UPDATE "Project"
-    SET "onboardingState" = ${sql.json(onboardingState)}
+    SET "onboardingState" = ${sql.json(onboardingState)}::jsonb
     WHERE "id" = ${ctx.projectId}
   `;