ci: Enforce dev as base branch for development (#8369)

* Create repo-pr-enforce-base-branch.yml

* fix quotes

* test

* fix github token

* fix trigger and CLI config

* change back trigger because otherwise I can't test it

* fix the fix

* fix repo selection

* fix perms?

* fix quotes and newlines escaping in message

* Update repo-pr-enforce-base-branch.yml

* grrr escape sequences in bash

* test

* clean up

---------

Co-authored-by: Aarushi <50577581+aarushik93@users.noreply.github.com>

.github/workflows/repo-pr-enforce-base-branch.yml

@@ -0,0 +1,21 @@
+name: Repo - Enforce dev as base branch
+on:
+  pull_request_target:
+    branches: [ master ]
+    types: [ opened ]
+
+jobs:
+  check_pr_target:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Check if PR is from dev or hotfix
+        if: ${{ !(startsWith(github.event.pull_request.head.ref, 'hotfix/') || github.event.pull_request.head.ref == 'dev') }}
+        run: |
+          gh pr comment ${{ github.event.number }} --repo "$REPO" \
+            --body $'This PR targets the `master` branch but does not come from `dev` or a `hotfix/*` branch.\n\nAutomatically setting the base branch to `dev`.'
+          gh pr edit ${{ github.event.number }} --base dev --repo "$REPO"
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+          REPO: ${{ github.repository }}