GHSA-p2q9-36vw-c468: olm-sys: wrapped library unmaintained, potentially vulnerable

After several cryptographic vulnerabilities in libolm were disclosed publicly, the Matrix Foundation has officially deprecated the library. olm-sys is a thin wrapper around libolm and is now deprecated and potentially vulnerable in kind.

Users of olm-sys and its higher-level abstraction, olm-rs, are highly encouraged to switch to vodozemac as soon as possible. It is the successor effort to libolm and is written in Rust.