ci: Restrict sementic PR to validate PR title only (#804)

.github/semantic.yml

@@ -1,3 +1,17 @@
+# Always validate the PR title, and ignore the commits
+titleOnly: true
+
+# Always validate all commits, and ignore the PR title
+commitsOnly: false
+
+# Always validate the PR title AND all the commits
+titleAndCommits: false
+
+# Require at least one commit to be valid
+# this is only relevant when using commitsOnly: true or titleAndCommits: true,
+# which validate all commits by default
+anyCommit: false
+
 # By default types specified in commitizen/conventional-commit-types is used.
 # See: https://github.com/commitizen/conventional-commit-types/blob/v2.3.0/index.json
 # You can override the valid types
@@ -12,3 +26,7 @@ types:
   - chore
   - skip changelog
   - skip ci
+
+# Allow use of Merge commits (eg on github: "Merge branch 'master' into feature/ride-unicorns")
+# this is only relevant when using commitsOnly: true (or titleAndCommits: true)
+allowMergeCommits: false