Use body-path for checklist in main-reviewer.yml

Author: RayStick

.github/workflows/main-reviewer.yml

@@ -31,5 +31,4 @@ jobs:
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           issue-number: ${{ github.event.pull_request.number }}
-          body: |
-            $(cat filled_checklist.md)
+          body-path: filled_checklist.md