ci: Phrase error in a way that gives a hint on how to fix problem

The passive phrasing makes it sound like there's something inherently
broken with the commit, rather than simply being missing an annotation
that the author can add.

Closes: #1809

.gitlab-ci/check-commit-log.sh

@@ -44,7 +44,7 @@ for commit in $commits; do
   commit_short=$(echo $commit | cut -c -8)
 
   if ! commit_message_has_url $commit; then
-    echo "Missing merge request or issue URL on commit $commit_short"
+    echo "Commit $commit_short needs a merge request or issue URL"
     exit 1
   fi