message: Use i64 instead of isize for representing Go's time.Duration type
diff: @@ -99,7 +99,7 @@ pub struct ConsumerConfig {
  pub ack_policy: AckPolicy,
  /// How long to allow messages to remain un-acknowledged before attempting redelivery
  #[serde(default, skip_serializing_if = "is_default")]
  - pub ack_wait: isize,
  + pub ack_wait: i64,
  /// Maximum number of times a specific message will be delivered. Use this to avoid poison pill messages that repeatedly crash your consumer processes forever.
  #[serde(default, skip_serializing_if = "is_default")]
  pub max_deliver: i64,
  @@ -551,7 +551,7 @@ pub(crate) struct SubOpts {
  /// Options for publishing
  #[derive(Debug, Default, Serialize, Deserialize, Clone)]
  pub(crate) struct PubOpts {
  - pub ttl: isize,
  + pub ttl: i64,
  pub id: String,
  // Expected last msgId
  pub lid: String,
  