fix: block incompatible kernel from being installed

The current "Requires" lines only ensure the old kernel is
available on the system but it does not prevent fedora from
updating to an incompatible and breaking user's system.

Set Conflicts to block incompatible kernels from being installed.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: tleydxdy <shironeko.github@tesaguri.club>
Closes #16139