build(deps-dev): Bump web-ext from 4.1.0 to 4.2.0 in /addon (#503)

Bumps [web-ext](https://github.com/mozilla/web-ext) from 4.1.0 to 4.2.0.
- [Release notes](https://github.com/mozilla/web-ext/releases)
- [Commits](mozilla/web-ext@4.1.0...4.2.0)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]