backup-exclude: Add suricata ruleset-sources to backup exclude file

backup-exclude: Add suricata ruleset-sources to backup exclude file

- This will ensure that an old version will no longer be restored back onto a users
   system.
- The suricata ruleset-sources file should also be shipped in the CU that this will be
   applied to make sure that all usders have the correct version installed, in case they
   have done a restore from an old backup after doing a fresh install.
- Tested on my vm testbed system and after making the change, the ruleset-sources file
   is no longer added to the backup set but also it is excluded from the restore if it
   is included in an old backup.

Tested-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>