COMP: Add cmake_minimum_required to top level CMakeLists.txt
COMP: Add cmake_minimum_required to top level CMakeLists.txt

My review was wrong in #48 -- we do need `cmake_minimum_required` when building the modules as a separate project :man_shrugging: .

This should fix the Linux Python wrapping build.

Using version 3.10.2 because this is the current version required by ITK for compatibility with Linux distributions.
thewtex/TubeTK,aylward/ITKTubeTK,aylward/ITKTubeTK,thewtex/TubeTK,thewtex/TubeTK,aylward/ITKTubeTK,thewtex/TubeTK,aylward/ITKTubeTK