Bump @grpc/grpc-js from 1.3.2 to 1.12.0 in /frontend (#490)

Bumps [@grpc/grpc-js](https://github.com/grpc/grpc-node) from 1.3.2 to 1.12.0.
- [Release notes](https://github.com/grpc/grpc-node/releases)
- [Commits](https://github.com/grpc/grpc-node/compare/@grpc/grpc-js@1.3.2...@grpc/grpc-js@1.12.0)

---
updated-dependencies:
- dependency-name: "@grpc/grpc-js"
  dependency-type: indirect
...

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