Fix formatting for merge failed message (#95234)
Fixes formatting so that the merge rule shows up on a different line than the "Raised by" text
Follow up to https://github.com/pytorch/pytorch/pull/94932
New version
<img width="433" alt="image" src="https://user-images.githubusercontent.com/4468967/220441349-ac99096d-590a-42c1-b995-4a23b2d9b810.png">
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95234
Approved by: https://github.com/huydhn
