fix: update changelog generation script syntax

Correct the quote style in the changelog generation script for 
consistency and adherence to shell syntax. The change improves 
readability and reduces potential parsing issues.

Release.gitlab-ci.yml

@@ -28,7 +28,7 @@ unbound_release_changelog:
   script:
   - 'echo "Generating changelog"'
   - 'git-cliff --bump --unreleased --strip header > CHANGES.md'
-  - 'git-cliff --bump | sed '\''s/\s\+$//'\'' > CHANGELOG.md'
+  - "git-cliff --bump | sed 's/\s\+$//' > CHANGELOG.md"
   - 'echo "Bumping version"'
   - 'git-cliff --bumped-version 2>/dev/null > VERSION'
   artifacts: