Update Rust crate hmac to 0.12

Author: renovate-bot

Cargo.lock

@@ -16,5 +16,5 @@ path = "lib.rs"
 base64 = "0.13"
 chrono = "0.4"
 sha-1 = "0.9"
-hmac = "0.11"
+hmac = "0.12"
 reqwest = { version = "0.11", features = ["blocking"] }