Add pr title linter workflow (#6)

.github/workflows/pr-title.yml

@@ -0,0 +1,50 @@
+name: 'Validate PR title'
+
+on:
+  pull_request_target:
+    types:
+      - opened
+      - edited
+      - synchronize
+
+jobs:
+  main:
+    name: Validate PR title
+    runs-on: ubuntu-latest
+    steps:
+      # Please look up the latest version from
+      # https://github.com/amannn/action-semantic-pull-request/releases
+      - uses: amannn/action-semantic-pull-request@v4
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          # Configure which types are allowed.
+          # Default: https://github.com/commitizen/conventional-commit-types
+          types: |
+            feat
+            fix
+            improvement
+            docs
+            refactor
+            test
+            ci
+            chore
+          # Configure that a scope must always be provided.
+          requireScope: false
+          # Configure additional validation for the subject based on a regex.
+          # This example ensures the subject starts with an uppercase character.
+          subjectPattern: ^[A-Z].+$
+          # If `subjectPattern` is configured, you can use this property to override
+          # the default error message that is shown when the pattern doesn't match.
+          # The variables `subject` and `title` can be used within the message.
+          subjectPatternError: |
+            The subject "{subject}" found in the pull request title "{title}"
+            didn't match the configured pattern. Please ensure that the subject
+            starts with an uppercase character.
+          # For work-in-progress PRs you can typically use draft pull requests
+          # from Github. However, private repositories on the free plan don't have
+          # this option and therefore this action allows you to opt-in to using the
+          # special "[WIP]" prefix to indicate this state. This will avoid the
+          # validation of the PR title and the pull request checks remain pending.
+          # Note that a second check will be reported if this is enabled.
+          wip: true