ci(workflows/commitlint): add to repo [skip ci]

* Automated using https://github.com/myii/ssf-formula/pull/172

.github/workflows/commitlint.yml

+# -*- coding: utf-8 -*-
+# vim: ft=yaml
+---
+name: Commitlint
+'on': [pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    env:
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: wagoid/commitlint-github-action@v1