Update to Bevy 0.15

[ptsd]

Hi, thanks for this super useful package 😄.

This is basically just deps and deprecation changes but I needed it so might as well save you the hassle 👍

Todo:

• Update to non-rc deps for bevy when available
• Remove bevy_spectator crates.io patch when upstream updates (see: Update to Bevy 0.15 bevy_spectator#14)

[Shatur]

Thank you :)

[onkoe]

By the way, if you're having trouble with an error that says something like this:

barrett@fedora ~/D/p/c/bevy_atmosphere (bevy-0.15)> cargo check
    Checking bevy_atmosphere v0.10.0 (/home/barrett/Documents/projects/contributions/bevy_atmosphere)
error[E0432]: unresolved import `bevy::image`
 --> src/pipeline.rs:8:5
  |
8 |     image::Image,
  |     ^^^^^ could not find `image` in `bevy`

error[E0432]: unresolved import `bevy::image`
 --> src/skybox.rs:4:5
  |
4 |     image::Image,
  |     ^^^^^ could not find `image` in `bevy`

error[E0433]: failed to resolve: could not find `image` in `bevy`
  --> src/skybox.rs:23:10
   |
23 | #[derive(AsBindGroup, TypePath, Debug, Clone, Asset)]
   |          ^^^^^^^^^^^ could not find `image` in `bevy`
   |
   = note: this error originates in the derive macro `AsBindGroup` (in Nightly builds, run with -Z macro-backtrace for more info)

(snip...)

It is being caused by this Bevy 0.15.0 bug: bevyengine/bevy#16563

As a workaround, you can enable any image-like feature in Bevy, including png:

[dependencies]
bevy = { version = "0.15.0", default-features = false, features = [
  "bevy_asset",
  "bevy_render",
  "bevy_pbr",
  # "png",
] }