get_modern_cmake - version 3?

[snowman2]

Currently it attempts to get 28, but the default cmake version is 3.21.3.

multibuild/library_builders.sh

Lines 193 to 195 in b35c219

	if [ "`yum search cmake | grep ^cmake28\.`" ]; then
	cmake=cmake28
	fi

$ docker run --rm -it --entrypoint bash --network host quay.io/pypa/manylinux2010_i686:latest
# yum search cmake | grep ^cmake
cmake-fedora.noarch : CMake helper modules for fedora developers
cmake-gui.i686 : Qt GUI for cmake
cmake28-gui.i686 : Qt GUI for cmake28
cmake3-data.noarch : Common data-files for cmake3
cmake3-doc.noarch : Documentation for cmake3
cmake3-gui.i686 : Qt GUI for cmake3
cmake.i686 : Cross-platform make system
cmake28.i686 : Cross-platform make system
cmake3.i686 : Cross-platform make system
# cmake --version
cmake version 3.21.3

Is there a reason not to use version 3?

[mattip]

I think that stanza is really outdated. We can just remove it. The function also does not check if cmake is currently installed already, as it is in most current CI images.