Add release branch push triggers to rocm-mi300.yml (pytorch#149517)

When we added the rocm-mi300.yml earlier this year, we had lower capacity and we were just pipecleaning the workflow, so we set the trigger to only respond to pushes to main branch. But now we have more stability as well as capacity, and we would really like to ensure that the release branch is being tested on MI300s as well.

Pull Request resolved: pytorch#149517
Approved by: https://github.com/atalman

Author: jithunnair-amd

.github/workflows/rocm-mi300.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - release/*
     tags:
       - ciflow/rocm-mi300/*
   workflow_dispatch: