According to Miklos Vajna, we already write markup which is newer than
1.4, but the PDF version was not changed.

Printing still sets the version to 1.4, not sure if we should update it
or keep the old version.

Change-Id: I5387fba03a3ee33f18e16033f630f1b765e3df8f
Reviewed-on: https://gerrit.libreoffice.org/53373Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>