build(deps-dev): bump @grpc/grpc-js from 1.7.1 to 1.8.1 (#357)

Bumps [@grpc/grpc-js](https://github.com/grpc/grpc-node) from 1.7.1 to 1.8.1.
- [Release notes](https://github.com/grpc/grpc-node/releases)
- [Commits](https://github.com/grpc/grpc-node/commits)

---
updated-dependencies:
- dependency-name: "@grpc/grpc-js"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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