Create update-ac.yml workflow

.github/workflows/update-ac.yml

+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/
+
+name: "Update Android-Components"
+
+on:
+  schedule:
+    - cron: '*/15 * * * *'
+
+jobs:
+  main:
+    name: "Update Android-Components"
+    runs-on: ubuntu-20.04
+    steps:
+      - name: "Update Android-Components"
+        uses: mozilla-mobile/relbot@master
+        if: github.repository == 'mozilla-mobile/fenix'
+        with:
+          project: fenix
+          command: update-android-components
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}