Update num-derive requirement from 0.3 to 0.4 (#284)

Updates the requirements on [num-derive](https://github.com/rust-num/num-derive) to permit the latest version.
- [Changelog](https://github.com/rust-num/num-derive/blob/master/RELEASES.md)
- [Commits](rust-num/num-derive@num-derive-0.3.0...num-derive-0.4.0)

---
updated-dependencies:
- dependency-name: num-derive
  dependency-type: direct:production
...

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

Cargo.toml

@@ -41,7 +41,7 @@ bit-vec = "0.6.2"
 speedy = "0.8.0"
 log = "0.4.11"
 num-traits = "0.2"
-num-derive = "0.3"
+num-derive = "0.4"
 serde = { version = "1.0", features = ["derive"] }
 serde_repr="0.1"
 byteorder = { version = "1.3", features = ["i128"] }