Bump middleman from 4.3.1 to 4.3.2
Bump middleman from 4.3.1 to 4.3.2

Bumps [middleman](https://github.com/middleman/middleman) from 4.3.1 to 4.3.2.
- [Release notes](https://github.com/middleman/middleman/releases)
- [Changelog](https://github.com/middleman/middleman/blob/v4.3.2/CHANGELOG.md)
- [Commits](https://github.com/middleman/middleman/compare/v4.3.1...v4.3.2)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
thoughtbot/bourbon.io,thoughtbot/bourbon.io,thoughtbot/bourbon.io,thoughtbot/bourbon.io