Bump braces, webpack and web-ext

Bumps [braces](https://github.com/micromatch/braces) to 3.0.3 and updates ancestor dependencies [braces](https://github.com/micromatch/braces), [webpack](https://github.com/webpack/webpack) and [web-ext](https://github.com/mozilla/web-ext). These dependencies need 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 `webpack` from 4.46.0 to 5.91.0
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v4.46.0...v5.91.0)

Updates `web-ext` from 2.9.3 to 8.1.0
- [Release notes](https://github.com/mozilla/web-ext/releases)
- [Commits](mozilla/web-ext@2.9.3...8.1.0)

---
updated-dependencies:
- dependency-name: braces
  dependency-type: indirect
- dependency-name: webpack
  dependency-type: direct:development
- dependency-name: web-ext
  dependency-type: direct:development
...

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

Author: dependabot[bot]