proto v0.21 - Linux x64 musl support

This is a very small release that primarily adds support for the Linux x64 musl target.

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Thanks to cargo-dist, we can now build and distribute musl binaries with relative ease. When building the binary, libraries are statically linked to ensure that the binary can run on any Linux distribution.

You can download the binary from the official GitHub release or by running the Bash installation script. In the future, we plan to support arm64 builds for both Linux gnu and musl.

Other changes

View the official release for a full list of changes.

• Improved file and directory locking. Will now work correctly across processes and signals, especially for those killed/dropped.
• Updated WASM functions to use explicit Rust enum types for versions to properly handle all variations (version, alias, requirement, range).