[PROJ] Bump CMake version for PROJ 7.0

[Greg Troxel]

Howard Butler <howard at hobu.co> writes:

> +1
>
> I wonder if we could increase the minimum CMake requirement
> significantly further due to the fact that PROJ supports both CMake
> and autoconf for now. Do the packagers have an opinion on the topic?

I was going to comment that a proposal with no analysis and no rationale
was a little odd...

My opinion is that it's not a good thing to increase the required
version of dependencies for no good reason, unless it is truly free.
So I would look at the places one might want to build proj and see how
old cmake might be.

>From the pkgsrc point of view, we have 3.16.1 in our latest quarterly
release, and I suspect some kind of Ubuntu LTS or Centos LTS will be the
long pole in the tent.   So if there is a shared notion  that some
particular version is the oldest that is likely to be encountered -- on
a platform which can otherwise buidl proj -- then moving to that seems
reasonable, just for housekeeping,