Bump @grpc/grpc-js from 1.10.8 to 1.10.9 in /firebase/functions (#268)

Bumps [@grpc/grpc-js](https://github.com/grpc/grpc-node) from 1.10.8 to 1.10.9.
- [Release notes](https://github.com/grpc/grpc-node/releases)
- [Commits](https://github.com/grpc/grpc-node/compare/@grpc/[email protected]...@grpc/[email protected])

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

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Author: dependabot[bot]