CMake error due to gRPC

The following error appears when running cmake command:
```bash
~/Desktop/RadialGM/build$ cmake ..
```
```
CMake Error at CMakeLists.txt:248 (find_package):
Found package configuration file:

/usr/local/lib/cmake/grpc/gRPCConfig.cmake

but it set gRPC_FOUND to FALSE so package "gRPC" is considered to be NOT
FOUND. Reason given by package:

The following imported targets are referenced, but are missing:
protobuf::libprotobuf protobuf::libprotoc
```

Reproduce the failure with `cmake ..` from the `build` directory and inspect `CMakeLists.txt` at line 248, along with `/usr/local/lib/cmake/grpc/gRPCConfig.cmake`. Trace why the referenced protobuf targets are missing; done means the configuration completes without the reported gRPC package error.

Written by the indexing model from the issue text.