Bump webpack from 5.88.2 to 5.91.0 in /glean

Bumps [webpack](https://github.com/webpack/webpack) from 5.88.2 to 5.91.0.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v5.88.2...v5.91.0)

---
updated-dependencies:
- dependency-name: webpack
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]