Bump braces from 3.0.2 to 3.0.3 in /test/webpack

Bumps [braces](https://github.com/micromatch/braces) from 3.0.2 to 3.0.3.
- [Changelog](https://github.com/micromatch/braces/blob/master/CHANGELOG.md)
- [Commits](micromatch/braces@3.0.2...3.0.3)

---
updated-dependencies:
- dependency-name: braces
  dependency-type: indirect
...

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