Bump regex from 1.4.0 to 1.4.1 in /blacksmith

Bumps [regex](https://github.com/rust-lang/regex) from 1.4.0 to 1.4.1.
- [Release notes](https://github.com/rust-lang/regex/releases)
- [Changelog](https://github.com/rust-lang/regex/blob/master/CHANGELOG.md)
- [Commits](rust-lang/regex@1.4.0...1.4.1)

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

Author: dependabot-preview[bot]