chore(deps): upgrade grpc-js to 1.12.7 (#4707)

`@grpc/grpc-js` sat at 1.12.6 in the lockfile. `dockerode` is the only
consumer and already declares `^1.11.1`, so a scoped override is enough:

```json
"@grpc/grpc-js@>=1.12.0 <1.12.7": "1.12.7"
```

Pinned exactly to stay on the 1.12 line; a caret would pull 1.14.x.