build(git): add auto-merge master into dev workflow (#67)

.github/workflows/auto-master-dev-merge.yml

@@ -0,0 +1,26 @@
+name: Auto-merge master into dev
+
+on:
+  pull_request:
+    branches: [master]
+    types: [closed]
+
+jobs:
+  auto-merge:
+    if: github.event.pull_request.merged == true
+    timeout-minutes: 2
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository code
+        uses: actions/checkout@v4
+      - name: Set Git config
+        run: |
+          git config --local user.email "actions@github.com"
+          git config --local user.name "Github Actions"
+      - name: Merge master back to dev
+        run: |
+          git fetch --unshallow
+          git checkout dev
+          git pull
+          git merge --no-ff master -m "chore(git): auto-merge master -> dev"
+          git push