Rust patches libssh2 CVEs in 1.96.1 maintenance update

The Rust team released version 1.96.1, a maintenance update addressing operational and security issues in the toolchain. The release implements missing HTTP retry/timeout logic in Cargo's client and corrects a miscompilation bug in MIR optimization. It also patches three vulnerabilities in Cargo's bundled libssh2: CVE-2025-15661, CVE-2026-55199, and CVE-2026-55200. Users can upgrade via rustup update stable. This marks the first stable release to include HTTP resilience improvements for network-dependent operations.