Use tgymnich/fork-sync to create PR from upstream merge

Should be able to create upstream to main merge PR.

Uses https://github.com/marketplace/actions/fork-sync  for creating PR
Uses octokit , e.g. https://octokit.github.io/rest.js/v19#repos-get

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

.github/workflows/sync-fork.yml

@@ -0,0 +1,17 @@
+name: sync fork with upstream
+
+on:
+  schedule:
+    - cron: '11 8 * * 1' # 8:11 UTC on Monday
+
+  workflow_dispatch: # for manual testing
+
+jobs:
+  sync-fork-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: tgymnich/fork-sync@v1.7
+        with:
+          owner: grafana
+          base: main
+          head: main