Update validator requirement from 0.8 to 0.9
Update validator requirement from 0.8 to 0.9

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

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
svenstaro/rust-web-boilerplate,svenstaro/rust-web-boilerplate