Remove ref parameter from checkout action (#964)

Remove parameter to match https://github.com/linode/linode-cloud-controller-manager/blob/main/.github/workflows/pr-labeler.yml

Author: AshleyDumaine

.github/workflows/pr-labeler.yml

@@ -20,7 +20,6 @@ jobs:
         uses: actions/checkout@v6
         with:
           fetch-depth: 0
-          ref: ${{ github.event.pull_request.head.sha }}
       - name: Label PR
         uses: release-drafter/release-drafter@v6
         with: