Fix github build failures because of vdevprops.7

This small fix adds the manpage vdevprops.7 to the file
contrib/debian/openzfs-zfsutils.install and the github
actions will work again.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #14553