mina-signer/Cargo: bump up minimal version of thiserror to 2

With the current major version, no-std support is not possible.
See release notes for 2.0.0:
https://github.com/dtolnay/thiserror/releases/tag/2.0.0.

Author: dannywillems

Cargo.lock

@@ -77,7 +77,7 @@ sha3 = "0.10.8"
 spmc = "=0.3.0"
 strum = "0.26.1"
 strum_macros = "0.26.1"
-thiserror = "1.0.30"
+thiserror = { version = "2", default-features = false }
 tinytemplate = "1.1"
 wasm-bindgen = "=0.2.87"
 wasm-bindgen-test = ">=0.3.0"