Automatically derive a Default impl (#180)

Deriving Default for enums was stabilized in 1.62.0.

Cargo.toml

@@ -6,6 +6,7 @@ edition = "2018"
 description = "A native Rust implementation of ZeroMQ"
 license = "MIT"
 repository = "https://github.com/zeromq/zmq.rs"
+rust-version = "1.62.0"
 
 [features]
 default = ["tokio-runtime", "all-transport"]

src/codec/mechanism.rs

@@ -4,19 +4,14 @@ use std::convert::TryFrom;
 use std::fmt::Display;
 
 #[allow(clippy::upper_case_acronyms)]
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, Default)]
 pub enum ZmqMechanism {
+ #[default]
  NULL,
  PLAIN,
  CURVE,
 }
 
-impl Default for ZmqMechanism {
- fn default() -> Self {
- ZmqMechanism::NULL
- }
-}
-
 impl ZmqMechanism {
  pub const fn as_str(&self) -> &'static str {
  match self {