Bump protobufjs from 7.5.4 to 7.5.6 in /integration-tests

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) from 7.5.4 to 7.5.6.
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/protobufjs-v7.5.6/CHANGELOG.md)
- [Commits](protobufjs/protobuf.js@protobufjs-v7.5.4...protobufjs-v7.5.6)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-version: 7.5.5
  dependency-type: indirect
...

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

Author: dependabot[bot]