Update hex requirement from 0.3 to 0.4
Update hex requirement from 0.3 to 0.4

Updates the requirements on [hex](https://github.com/KokaKiwi/rust-hex) to permit the latest version.
- [Release notes](https://github.com/KokaKiwi/rust-hex/releases)
- [Commits](https://github.com/KokaKiwi/rust-hex/commits)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
rust-lang/cargo,vojtechkral/cargo,nipunn1313/cargo,rust-lang/cargo,nipunn1313/cargo,tshepang/cargo,tshepang/cargo,tsurai/cargo,rustyhorde/cargo,eminence/cargo,tshepang/cargo,vojtechkral/cargo,rust-lang/cargo,vojtechkral/cargo,tshepang/cargo,rustyhorde/cargo,eminence/cargo,tsurai/cargo,eminence/cargo,nipunn1313/cargo,vojtechkral/cargo,rustyhorde/cargo,tsurai/cargo,rust-lang/cargo,rustyhorde/cargo,nipunn1313/cargo,tsurai/cargo,tsurai/cargo,eminence/cargo