Version 1.8.1: Reduced enemy size, Reworked OSIRIS, and QOL updates

Enemies have been scaled down by 25%.

This solves a lot of problems with enemies preventing each other from moving.

The OSIRIS boss fight now has frenzy bullets, and he evolves each time you fight him.

OSIRIS felt a bit too easy and stagnant these changes are designed to fix that.

Arena spawning and difficulty have been improved.

Arena spawning and OSIRIS enemy spawning have been changed to scale better with each difficulty level and with the current OSIRIS boss level. This makes the game progression better match the player progression.