War Brokers v503 Update

- Fix for fire rate on client for Desert pistol
- When gasser alien explodes, their cloud is larger
- Fix for Gold Mine level not loading on Linux and Mac
- Fix for solid color textures on certain outfits
- Add attachments to G3A3 in Battle Royale and Dead City modes
- Update items in reward crates for Alien Dead City
- Tweak enemy spawn rates in Alien Dead City
- Update audio for G3A3