ci: update global workflows

.github/workflows/autoupdate.yml

@@ -0,0 +1,32 @@
+---
+# This action is centrally managed in https://github.com/<organization>/.github/
+# Don't make changes to this file in this repo as they will be overwritten with changes made to the same file in
+# the above-mentioned repo.
+
+# This workflow is designed to work with:
+# - automerge workflows
+
+# It uses GitHub Action that auto-updates pull requests branches, when changes are pushed to their destination branch.
+# Auto-updating to the latest destination branch works only in the context of upstream repo and not forks.
+
+name: autoupdate
+
+on:
+  push:
+    branches:
+      - 'nightly'
+
+jobs:
+  autoupdate-for-bot:
+    name: Autoupdate autoapproved PR created in the upstream
+    if: startsWith(github.repository, 'LizardByte/')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Update
+        uses: docker://chinthakagodawita/autoupdate-action:v1
+        env:
+          GITHUB_TOKEN: '${{ secrets.GH_BOT_TOKEN }}'
+          PR_FILTER: "labelled"
+          PR_LABELS: "autoupdate"
+          PR_READY_STATE: "ready_for_review"
+          MERGE_CONFLICT_ACTION: "ignore"