gitlint: Allow trivial changes to be without refernce (SOC-9559)

The author of a commit should make a conscious decision to either add a
reference or not. Adding trivial instead of bsc or SOC enables this.
This change prevents that adding a refernce is forgotten as the
syntax requires to think about it.

See
SUSE-Cloud#3509 (comment)
for more details.

scripts/jenkins/gitlint.ini

@@ -8,7 +8,7 @@ line-length=80
 words=wip,WIP
 
 [title-match-regex]
-regex=^(?!SOC).*\(((bsc#|SOC-)[0-9]+(,\s)?)+\)$
+regex=^(?!SOC).*\((((bsc#|SOC-)[0-9]+(,\s)?)+|trivial)\)$
 
 [body-max-line-length]
 line-length=80