Add create plugin update workflow (#2074)

.github/workflows/update-create-plugin.yml

@@ -0,0 +1,16 @@
+name: Create Plugin Update
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 0 1 * *' # run once a month on the 1st day
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: grafana/plugin-actions/create-plugin-update@main