.github/workflow/kernel-build-and-test-x86_64.yml: Use PRIVATE REPO ACCESS TOKEN to create a pull request

Otherwise the workflow when a pull request is created won't be triggered.

Signed-off-by: Roxana Nicolescu <rnicolescu@ciq.com>

Author: roxanan1996

.github/workflows/kernel-build-and-test-x86_64.yml

@@ -483,7 +483,7 @@ jobs:
 
     - name: Create Pull Request
       env:
-        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        GH_TOKEN: ${{ secrets.PRIVATE_REPO_ACCESS_TOKEN }}
       run: |
         # Reuse base branch from compare-results stage (already computed)
         BASE_BRANCH="${{ needs.compare-results.outputs.base_branch }}"