EPUB3 was released in 2011, it makes little sense to target the older
EPUB2 in new code.

Change-Id: Ifdd547bfc7e8f097124ed3effe9053ee2e5f2163
Reviewed-on: https://gerrit.libreoffice.org/40975Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>