Update num requirement from 0.2 to 0.3

Updates the requirements on [num](https://github.com/rust-num/num) to permit the latest version.
- [Release notes](https://github.com/rust-num/num/releases)
- [Changelog](https://github.com/rust-num/num/blob/master/RELEASES.md)
- [Commits](rust-num/num@num-0.2.0...num-0.3.0)

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

Author: dependabot-preview[bot]

Cargo.toml

@@ -6,4 +6,4 @@ edition = "2018"
 
 [dependencies]
 rand = "0.7"
-num = "0.2"
+num = "0.3"