v0.5.2 - Schedulers and updated dependency installer

Added the ability to change schedulers to a user-specified one.

Added latest diffusers library which has added support for Stable Diffusion 2.0.

Assets have been upgraded to 5.1 so moving forwards, I'll be focusing on maintaining the 5.1 version as it's a bit harder to downgrade assets to 5.0. If there is a high demand for 5.0 then I'll look into downgrading the assets.