chore: Auto assign PR (#3531)

## About the changes
This will auto-assign any PR to the opener of the PR. This should help
identify internal PRs from external ones, mainly helping our GitHub
Watcher role

PoC done in unleash-edge:
https://github.com/Unleash/unleash-edge/actions/workflows/auto-assign-pr-author.yaml

.github/workflows/auto-assign-pr-author.yaml

@@ -0,0 +1,14 @@
+name: Auto Assign Author
+
+on:
+  pull_request_target:
+    types: [opened, reopened]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  assign-author:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: toshimaru/auto-author-assign@v1.6.2