This change is for fix warning:
```
CMake Warning (dev) at /home/aoleksy/share/cmake-3.17/Modules/FindPackageHandleStandardArgs.cmake:272 (message):
The package name passed to `find_package_handle_standard_args`
(flatbuffers) does not match the name of the calling package (FlatBuffers).
This can lead to problems in calling code that expects `find_package`
result variables (e.g., `_FOUND`) to follow a certain pattern.
Call Stack (most recent call first):
FindFlatBuffers.cmake:33 (find_package_handle_standard_args)
CMakeLists.txt:6 (find_package)
This warning is for project developers. Use -Wno-dev to suppress it.
```
Adam Oleksy