Update @types/webpack requirement from 4.4.17 to 4.4.18 (#3194)

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

)

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