Bump proto-plus from 1.19.9 to 1.20.0 in /requirements (#18791)
Bump proto-plus from 1.19.9 to 1.20.0 in /requirements (#18791)

Bumps [proto-plus](https://github.com/googleapis/proto-plus-python) from 1.19.9 to 1.20.0.
- [Release notes](https://github.com/googleapis/proto-plus-python/releases)
- [Changelog](https://github.com/googleapis/proto-plus-python/blob/main/CHANGELOG.md)
- [Commits](https://github.com/googleapis/proto-plus-python/compare/v1.19.9...v1.20.0)

---
updated-dependencies:
- dependency-name: proto-plus
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
wagnerand/addons-server,mozilla/addons-server,mozilla/addons-server,mozilla/addons-server,mozilla/olympia,mozilla/addons-server,wagnerand/addons-server,diox/olympia,wagnerand/addons-server,mozilla/olympia,diox/olympia,mozilla/olympia,diox/olympia,diox/olympia,mozilla/olympia,wagnerand/addons-server