build(deps): update num-bigint requirement from 0.4 to 0.5 (#3)

Updates the requirements on [num-bigint](https://github.com/rust-num/num-bigint) to permit the latest version.
- [Changelog](https://github.com/rust-num/num-bigint/blob/main/RELEASES.md)
- [Commits](https://github.com/rust-num/num-bigint/compare/num-bigint-0.4.0...num-bigint-0.5.1)

---
updated-dependencies:
- dependency-name: num-bigint
  dependency-version: 0.5.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -20,7 +20,7 @@ serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 base64 = "0.23.1"
 tracing = "0.1"
-num-bigint = "0.4"
+num-bigint = "0.5"
 num-traits = "0.2"
 sha1 = "0.10"
 sha2 = "0.10"