[redhat] ark-create-release.sh: use 3-way merge
There can be conflicts that the 3-way merge strategy can resolve
when adding the Include in Releases MRs. Let 'git am' fall back to
use the 3-way merge strategy if the patch does not initially apply.
For example, !2975 (merged) and !3010 (merged) can be merged using git merge
but will fail using git am
.
Signed-off-by: Scott Weaver scweaver@redhat.com