fork: rebase action to keep in sync with upstream

.github/workflows/v3-rebase-dev-onto-upstream.yml

@@ -0,0 +1,30 @@
+name: Rebase v3/dev fork onto upstream v3-alpha
+
+on:
+  schedule:
+    - cron:  '0 7 * * 1,4'
+    # scheduled at 07:00 every Monday and Thursday
+  workflow_dispatch:  # click the button on Github repo!
+
+jobs:
+  sync_latest_from_upstream:
+    runs-on: ubuntu-latest
+    name: Sync latest commits from upstream repo
+
+    steps:
+      # Step 1: run a standard checkout action, provided by github
+      - name: Checkout target repo
+        uses: actions/checkout@v3
+        with:
+          # optional: set the branch to checkout,
+          ref:  v3/dev
+          # REQUIRED if your upstream repo is private (see wiki)
+          persist-credentials: false
+
+      # Step 2: run the sync action
+      - name: Rebase onto upstream changes
+        id: sync
+        uses: imba-tjd/rebase-upstream-action@0.5
+        with:
+          branch: v3-alpha
+          upstream: wailsapp/wails