Update the CMake minimum required to 2.8.12. (#95)
Update the CMake minimum required to 2.8.12. (#95)

This is to remove a warning that happens on modern CMake
(> 3.19), and shouldn't really cause too many compatibility
problems.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@openrobotics.org>
eProsima/Fast-CDR,eProsima/Fast-CDR,eProsima/Fast-CDR,eProsima/Fast-CDR