Bump num-bigint from 0.4.3 to 0.4.4 in /lang/rust (#2464)

Bumps [num-bigint](https://github.com/rust-num/num-bigint) from 0.4.3 to 0.4.4.
- [Changelog](https://github.com/rust-num/num-bigint/blob/master/RELEASES.md)
- [Commits](rust-num/num-bigint@num-bigint-0.4.3...num-bigint-0.4.4)

---
updated-dependencies:
- dependency-name: num-bigint
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

lang/rust/avro/Cargo.toml

@@ -61,7 +61,7 @@ digest = { default-features = false, version = "0.10.7", features = ["core-api"]
 lazy_static = { default-features = false, version = "1.4.0" }
 libflate = { default-features = false, version = "2.0.0", features = ["std"] }
 log = { default-features = false, version = "0.4.20" }
-num-bigint = { default-features = false, version = "0.4.3" }
+num-bigint = { default-features = false, version = "0.4.4" }
 regex-lite = { default-features = false, version = "0.1.0", features = ["std", "string"] }
 serde = { default-features = false, version = "1.0.185", features = ["derive"] }
 serde_json = { default-features = false, version = "1.0.105", features = ["std"] }