Add auto-update gh action

.github/workflows/update.yml

@@ -0,0 +1,30 @@
+name: Update
+on:
+  workflow_dispatch:
+  # Auto-update every week on midnight Monday
+  schedule:
+    - cron: '0 0 * * 1'
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: '12.x'
+          registry-url: 'https://registry.npmjs.org'
+      - name: Install dependencies
+        run: yarn
+      - name: Generate new files
+        run: yarn generate && yarn build
+      - name: Update version
+        run: yarn version --patch --no-git-tag-version
+      - name: Commit and push changes
+        uses: EndBug/add-and-commit@v9
+        with:
+          default_author: 'github_actions'
+          message: 'Update generated files'
+      - name: Publish to npm
+        run: yarn publish
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}