`The property "LINKER_LANGUAGE" is not allowed.` When Following Quick Start

My system:
- Ubuntu 20.04.5 LTS (Focal Fossa)
- `uname -m`: x86_64
- `cmake --version`: 3.16.3

Steps to repro.:
```
git clone https://github.com/google/flatbuffers
cd flatbuffers
cmake -G "Unix Makefiles"
```

Error message:
![](https://i.imgur.com/EfR6RQD.png)