Bump braces and watchpack in /webapp

Bumps [braces](https://github.com/micromatch/braces) and [watchpack](https://github.com/webpack/watchpack). These dependencies needed to be updated together.

Updates `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)

Updates `watchpack` from 1.6.1 to 1.7.5
- [Release notes](https://github.com/webpack/watchpack/releases)
- [Commits](webpack/watchpack@v1.6.1...v1.7.5)

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

Signed-off-by: dependabot[bot] <[email protected]>