fix: verifier retry logic

Adjust the logic retry logic in the Pact Verifier so that it:

- Retries on 5XX server errors, 429 Too Many Requests, and 408 Request
  Timeout.
- In the case of a 429, also parse the `Retry-After` header (if present)
  for the delay
- Tweak the exponential retry delay from millisecond decades starting
  from 1ms, to powers of 2 starting from 0.5s. It is unlikely that a 1ms
  delay will resolve the issue, but also going from 1s to 10s to 100s is
  quite a large increase.

Also took the opportunity to upgrade reqwest to 0.13.

Signed-off-by: JP-Ellis <josh@jpellis.me>

Author: JP-Ellis

rust/Cargo.lock

@@ -39,7 +39,8 @@ pact_matching = { version = "~2.0.3", path = "../pact_matching", default-feature
 pact_models = { version = "~1.3.10", default-features = false }
 pact-plugin-driver = { version = "~0.7.5", optional = true, default-features = false }
 regex = "1.12.3"
-reqwest = { version = "0.12.28", default-features = false, features = ["rustls-tls-native-roots", "blocking", "json"] }
+httpdate = "1.0"
+reqwest = { version = "0.13", default-features = false, features = ["rustls", "blocking", "json", "query"] }
 serde = "1.0.228"
 serde_json = "1.0.149"
 serde_with = { version = "3.16.1", features = ["json"] }
@@ -54,6 +55,7 @@ urlencoding = "2.1.3"
 crate-type = ["cdylib", "rlib"]
 
 [dev-dependencies]
+axum = "0.8"
 chrono = "0.4.43"
 chrono-tz = "0.10.4"
 env_logger = "0.11.9"

rust/pact_verifier/Cargo.toml

@@ -215,7 +215,7 @@ impl HALClientBuilder {
     self
   }
 
-  /// Sets the number of retries on certain HTTP errors. Default is 3.
+  /// Sets the number of retries on certain HTTP errors (5xx, 408, 429). Default is 3.
   pub fn with_retries(&mut self, retries: u8) -> &mut Self {
     self.retries = retries;
     self