Use milkmaker as PR author

Use template to be able to use get_diff var

.github/workflows/pr_to_nightly.yml

@@ -8,18 +8,18 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           fetch-depth: 0
       - name: Run the Action
         uses: devops-infra/action-pull-request@v0.5.0
         with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
+          github_token: ${{ secrets.PRTONIGHTLY_ACTION_PAT }}
           title: Automatic PR to nightly from ${{ github.event.repository.updated_at}}
           assignee: DerLinkman
           source_branch: staging
           target_branch: nightly
           reviewer: DerLinkman
           label: upstream
-          body: Merge current staging state to nightly branch
-          get_diff: true
+          template: .github/ISSUE_TEMPLATE/pr_to_nighty_template.yml
+          get_diff: true