Workaround to allow openzfs-zfs-dkms install on Ubuntu

As shown in #15404#issuecomment-1765002181, Ubuntu kernel has
'Provides: zfs-dkms', which will cause uninstall of the kernel, when
attempting to install openzfs-zfs-dkms.
As a workaround remove the 'Conflicts: zfs-dkms' definition from
the debian control file.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Mart Frauenlob <AllKind@fastest.cc>
Closes #15503

contrib/debian/control

@@ -197,7 +197,6 @@ Recommends: openzfs-zfs-zed, openzfs-zfsutils (>= ${source:Version}), ${linux:Re
 Suggests: debhelper
 Breaks: spl-dkms (<< 0.8.0~rc1)
 Replaces: spl-dkms, zfs-dkms
-Conflicts: zfs-dkms
 Provides: openzfs-zfs-modules
 Description: OpenZFS filesystem kernel modules for Linux
  OpenZFS is a storage platform that encompasses the functionality of