Bump prop-types from 15.6.1 to 15.7.2

Bumps [prop-types](https://github.com/facebook/prop-types) from 15.6.1 to 15.7.2.
- [Release notes](https://github.com/facebook/prop-types/releases)
- [Changelog](https://github.com/facebook/prop-types/blob/master/CHANGELOG.md)
- [Commits](facebook/prop-types@v15.6.1...v15.7.2)

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

Author: dependabot-preview[bot]