CI: Remove PR-specific step from nightly Windows build

Author: https://github.com/gmta
Commit: 8493f74be1
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5152
Reviewed-by: https://github.com/ADKaster ✅

.github/workflows/nightly-windows.yml

@@ -25,11 +25,6 @@ jobs:
       - uses: actions/checkout@v4
         if: ${{ github.event_name != 'pull_request' }}
 
-      - uses: actions/checkout@v4
-        if: ${{ github.event_name == 'pull_request' }}
-        with:
-          ref: refs/pull/${{ github.event.pull_request.number }}/merge
-
       - name: Set Up Environment
         uses: ./.github/actions/setup
         with: