devel/librashader: update to 0.4.5

Changes:
https://github.com/SnowflakePowered/librashader/releases/tag/librashader-v0.4.3
https://github.com/SnowflakePowered/librashader/releases/tag/librashader-v0.4.5

Version 0.4.3 allows building on stable Rust, so the port has switched from
building with lang/rust-nightly to lang/rust. When building on stable Rust,
upstream's librashader-build-script doesn't generate the C headers anymore.
The port has to package the pre-generated headers instead. This shouldn't
have any user-visible effects for consumers.

Version 0.4.4 was skipped due to a release configuration error.

PR: 281525
Event: EuroBSDcon 2024