Can we not unnecessarily bump requirements for kdav?

[Christian Mollekopf]

Hi,

Commit d40887c1581 which bumps the KF5_VERSION requirement from 5.27.0
to 5.31.0 for no reason,
which leaves me unable to build master on Fedora 25 without building all
the dependencies as well (and I have no reason to do so).

Can we please not bump the version requirement without a reason to do
so?

Otherwise I would have to:
* Maintain a branch that drops the requirement again (which seems
useless)
* Maintain a cmake option that drops the requirement (which again
doesn't make much sense IMO)

So I'd like to request that the aforementioned commit is reverted.

Thanks,
Christian