Bump protobufjs from 6.10.2 to 6.11.3 in /channels/chat21

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) from 6.10.2 to 6.11.3.
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/v6.11.3/CHANGELOG.md)
- [Commits](protobufjs/protobuf.js@v6.10.2...v6.11.3)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-type: indirect
...

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

Author: dependabot[bot]