CI with multiple cmake versions and related updates
- Add CI jobs with multiple cmake versions. Together with ranges in
cmake_minimum_requiredthis allows for reasonable checks of different sets of CMake policies. The jobs should be started manually. See also !386. - Fix c++14-only code in testIO30
- Remove obsolete checks of CMake version
- Update github CI to enable manual execution of CI jobs.
Edited by Andrii Verbytskyi