Bump mockito to 0.31.1

Fixes a RUSTSEC advisory where mockito was depending
on an unmaintained crate
lipanski/mockito#145

Author: Pi-Cla

Cargo.toml

@@ -45,7 +45,7 @@ base16 = { version = "0.2", features = ["alloc"] }
 # HTTP client
 reqwest = { version = "0.12", features = ["json"] }
 # HTTP mock server
-mockito = "0.30"
+mockito = "0.31.1"
 # Async runtime
 tokio = { version = "1", features = ["full"] }
 # toml encoding