chore: Remove ref option from checkout step in on-review workflow (hiero-ledger#2367)

Signed-off-by: Ntege Daniel <danientege785@gmail.com>

Author: danielmarv

.github/workflows/on-review.yml

@@ -34,7 +34,6 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
         with:
-          ref: ${{ github.event.pull_request.base.sha || github.ref }}
           persist-credentials: false
 
       - name: Run Add Reviewers as Assignees