CMake: Bump version to v0.24
CMake: Bump version to v0.24

Bump libiio version to v0.24, which should be the last version of the
v0.x series.

Signed-off-by: Paul Cercueil <a027184a55211cd23e3f3094f1fdc728df5e0500@crapouillou.net>

analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio