The short answer is to refactor your Puppet code into autoloadable modules with the structure described here: https://docs.puppetlabs.com/puppet/latest/reference/lang_namespaces.html
The reasoning for deprecating and eventually removing the
import keyword is as follows:
The distinction between import and
include/class declaration confuses
many users, and we've had a number of
edge cases with import that have
caused even more confusion.
forward is to structure your manifests
in classes in modules, and to follow
autoloader conventions. This does make
Puppet much more opinionated, but we
believe the benefits are worth it.
Particularly this will push people
towards a world where Puppet manifests
are more easily shareable in the form
of modules, and by running everyone
through the autoloader, we'll have a
much more consistent set of behaviors.
Hope that helps!