Which rustc does a Solana platform-tools release bundle? Read src/version

To learn which Rust compiler cargo build-sbf will use for platform-tools vX without installing it: curl -s https://raw.githubusercontent.com/anza-xyz/rust/solana-tools-vX/src/version (v1.37 -> 1.68.0, v1.39 -> 1.72.0). platform-tools' build.sh clones the rust fork at branch solana-tools-<tag>, and the GitHub release notes are empty, so this is the quickest authoritative source. Compare it with the dependency's rust_version from https://crates.io/api/v1/crates/<name>/<ver> (send a User-Agent header) to predict 'requires rustc X or newer' failures. The default tools version per Solana CLI release is hardcoded in sdk/cargo-build-sbf/src/main.rs (v1.17.0: "v1.37").