feat: add auto update for v3 branch (#27)

Author: mfranzke

.github/scripts/auto-update-pr.js

@@ -0,0 +1,25 @@
+module.exports = async ({ github, context }, head, base) => {
+	try {
+		const { repo, owner } = context.repo;
+		const result = await github.rest.pulls.create({
+			title: 'Auto Update from main',
+			owner,
+			repo,
+			head,
+			base,
+			body: '(o゜▽゜)o ☆ ☜(ﾟヮﾟ☜)'
+		});
+
+		await github.rest.issues.addLabels({
+			owner,
+			repo,
+			issue_number: result.data.number,
+			labels: ['automated update']
+		});
+
+		return result.data.html_url;
+	} catch (e) {
+		console.error(e);
+	}
+	return false;
+};

.github/workflows/99-auto-update-pr.yml

@@ -0,0 +1,44 @@
+---
+name: Auto Update PR
+
+on:
+  workflow_call:
+    inputs:
+      head:
+        required: true
+        type: string
+      base:
+        required: true
+        type: string
+
+permissions:
+  pull-requests: write
+  contents: write
+
+jobs:
+  create-pull-request:
+    runs-on: ubuntu-latest
+    steps:
+      - name: ⬇️ Checkout repo
+        uses: actions/checkout@v3
+
+      - name: ↔ Create Pull Request
+        uses: actions/github-script@v6
+        id: create-pr
+        with:
+          result-encoding: string
+          script: |
+            const script = require('./.github/scripts/auto-update-pr.js')
+            const head = '${{ inputs.head }}';
+            const base = '${{ inputs.base }}';
+            return await script({github, context}, head, base)
+            
+      - name: 🤖 Enable auto-merge for auto-update
+        run: |
+          if [[ $PR_URL != false ]];
+          then
+            gh pr merge --auto --merge "$PR_URL"
+          fi
+        env:
+          PR_URL: ${{steps.create-pr.outputs.result}}
+          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}

.github/workflows/auto-update.yml

@@ -0,0 +1,16 @@
+---
+name: Schedule Auto Update
+
+on:
+  schedule:
+    - cron: "0 0 * * *"
+
+jobs:
+  auto-update:
+    strategy:
+      matrix:
+        update: [{ head: "main", base: "v3" }]
+    uses: ./.github/workflows/99-auto-update-pr.yml
+    with:
+      head: ${{ matrix.update.head }}
+      base: ${{ matrix.update.base }}