build(deps): bump num-derive from 0.3.0 to 0.3.1

Bumps [num-derive](https://github.com/rust-num/num-derive) from 0.3.0 to 0.3.1.
- [Release notes](https://github.com/rust-num/num-derive/releases)
- [Changelog](https://github.com/rust-num/num-derive/blob/master/RELEASES.md)
- [Commits](rust-num/num-derive@num-derive-0.3.0...num-derive-0.3.1)

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

dependabot-preview committed Jul 29, 2020

a21f70e