Update script

.github/workflows/update.yaml

@@ -0,0 +1,31 @@
+name: Update to Upstream
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  schedule:
+    - cron: "*/30 * * * *"
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: configure
+      run: |
+          git config --global user.name 'Robot'
+          git config --global user.email '[email protected]'
+          # "git checkout main" is unnecessary, already here by default
+          git pull --unshallow  # this option is very important, you would get
+                                # complains about unrelated histories without it.
+                                # (but actions/checkout@v2 can also be instructed
+                                # to fetch all git depth right from the start)
+          git remote add upstream https://fuchsia.googlesource.com/fuchsia/
+          git fetch upstream
+          
+          git checkout main
+          git rebase upstream/main && git push -f origin main