IWYU is not REQUIRED

[Enriquefft]

https://github.com/Enriquefft/cpp-template/blob/ee881bf74d2dff901ef899cce30b8fac8fe3673f/CMakeLists.txt#L29C1-L29C56

Currently, the flag REQUIRED has been removed from IWYU find_program, this is due to the lack of a simple way to install it on windows.