add repo-sync configuration

Author: Alexander Smirnov

.github/workflows/repo-sync.yml

@@ -0,0 +1,25 @@
+name: Repo Sync
+
+on:
+  schedule:
+    - cron: "*/15 * * * *" # every 15 minutes
+
+jobs:
+  repo-sync:
+    name: Repo Sync
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: repo-sync/github-sync@v2
+        name: Sync repo to branch
+        with:
+          source_repo: ${{ secrets.SOURCE_REPO }}
+          source_branch: main
+          destination_branch: ${{ secrets.INTERMEDIATE_BRANCH }}
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+      - uses: repo-sync/pull-request@v2
+        name: Create pull request
+        with:
+          source_branch: ${{ secrets.INTERMEDIATE_BRANCH }}
+          destination_branch: main
+          github_token: ${{ secrets.GITHUB_TOKEN }}