nix: Clean up build (#27881)

- bump our livekit version to include a fix for a crane bug (TODO: add
link when an issue is filed on crane)
- switch to a clang stdenv for both linux and macos
- manually unify versions of our notify crate
- remove old linker flags which were only needed for livekit
- fix an issue where RUSTFLAGS shadowed the rustflags from cargo configs

Release Notes:

- N/A
4110928314Julia Ryan committed on 4/1/2025, 10:35:15 PM· committed by GitHubparenta1b53e9
9 files changedLine totals unavailable