in issue-bot/src/routes.rs [22:28]
fn compute_signature(payload: &[u8], secret: &str) -> String {
let key = Hmac::<Sha256>::new_from_slice(secret.as_bytes()).unwrap();
let mut mac = key;
mac.update(payload);
let result = mac.finalize().into_bytes();
format!("sha256={}", hex::encode(result))
}