Bump letter_opener_web from 1.4.1 to 2.0.0 (#16960)

Bumps [letter_opener_web](https://github.com/fgrehm/letter_opener_web) from 1.4.1 to 2.0.0.
- [Release notes](https://github.com/fgrehm/letter_opener_web/releases)
- [Changelog](https://github.com/fgrehm/letter_opener_web/blob/master/CHANGELOG.md)
- [Commits](https://github.com/fgrehm/letter_opener_web/compare/v1.4.1...v2.0.0

)

---
updated-dependencies:
- dependency-name: letter_opener_web
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>