Function resolve_commit_sha 

pub fn resolve_commit_sha(commit_ref: &str) -> Result<String>

Resolve a git ref to a full commit SHA.

Args:

• commit_ref: A git ref (branch name, tag, SHA, HEAD, etc.).

Usage:

let sha = resolve_commit_sha("HEAD")?;
let sha = resolve_commit_sha("v1.0.0")?;