updating the spawn manager

spawnmanager.cs

    IEnumerator SpawnPowerupRoutine()
    {
        //every 3 - 7 seconds, spawn in a powerup
        while (_stopSpawning == false) { 
        
            Vector3 spawn = new Vector3(Random.Range(-8f, 8f), 7, 0);

            int randomPowerUp = Random.Range(0, 4);
           Instantiate(_powerups[randomPowerUp], spawn, Quaternion.identity);
            yield return new WaitForSeconds(Random.Range(3, 8));
        }
    }