Upgrade to Bevy `0.15-dev` #747

Job	Run time
nix-fmt-check	26s
nix-flake-check (ubuntu-latest)	28s
cargo (cargo fmt --verbose --all -- --check)	56s
nix-flake-check (macos-latest)	58s
cargo (cargo check --locked --workspace)	4m 8s
cargo (cargo check --locked --examples --workspace)	4m 36s
cargo (cargo test --locked --lib --bins --workspace --features "egui")	7m 36s
cargo (cargo doc --locked --workspace --features "egui")	7m 47s
cargo (cargo test --locked -p nannou_core --no-default-features --features "libm serde")	1m 23s
cargo (mdbook build guide/)	58s
cargo (cargo test --locked -p book_tests)	7m 2s
verifications	1s
guide-push-to-deploy	0s
cargo-publish	0s
	36m 19s

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