manifest: Add workflow

.github/workflows/main.yml

@@ -0,0 +1,22 @@
+name: Test AmogOS-Rom/android_manifest repository
+
+on:
+  push:
+    branches: [ thirteen ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Install repo tool
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y git-core python3-pip wget
+          wget https://storage.googleapis.com/git-repo-downloads/repo && sudo mv repo /usr/bin/repo && sudo chmod a+x /usr/bin/repo
+      - name: Initialize and Sync Repo 
+        run: |
+          repo init -u https://github.com/AmogOS-Rom/android_manifest.git
+          timeout 1m repo sync || true
+        timeout-minutes: 6