build: Use modern CMake approach for versioning
build: Use modern CMake approach for versioning

As recommended by semantic versioning we use major.minor.patch now.

Signed-off-by: Alexander Dahl <9b466094ec991a03cb95c489c19c4d75635f0ae5@lespocky.de>

LeSpocky/libcgi,rafaelsteil/libcgi,LeSpocky/libcgi,rafaelsteil/libcgi