ci: 👷 add commit linting

Add commit linting according to the Conventional Commits spec.

.github/workflows/commit-lint.yml

@@ -0,0 +1,25 @@
+# SPDX-FileCopyrightText: none
+#
+# SPDX-License-Identifier: MIT
+
+---
+name: Conventional Commits
+on: [pull_request]
+
+jobs:
+  lint-commits:
+    name: Lint Commits
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout 🛎️
+        uses: actions/checkout@v2.3.1
+        with:
+          fetch-depth: 0
+      - name: Install Commit Linting Tool 🔧
+        run: npm install --save-dev @commitlint/{cli,config-conventional}
+      - name: Set Linting Config to Conventional Commits spec 🔧
+        run: |
+          echo "module.exports = { extends: ['@commitlint/config-conventional'] };" > commitlint.config.js
+      - name: Lint 🚨
+        run: npx commitlint --from HEAD~1 --to HEAD --verbose