Sync fork with upstream before creating PR branch

- Fetch latest upstream/master before making changes
- Ensures PR only shows requirements.txt diff, not stale commits
- Does not modify fork's master branch (only pushes automation branch)

.github/workflows/release-weekly-comfyui.yaml

@@ -143,6 +143,15 @@ jobs:
           token: ${{ secrets.PR_GH_TOKEN }}
           path: comfyui
 
+      - name: Sync with upstream
+        working-directory: comfyui
+        run: |
+          # Fetch latest upstream to base our branch on fresh code
+          # Note: This only affects the local checkout, NOT the fork's master branch
+          # We only push the automation branch, leaving the fork's master untouched
+          git fetch https://github.com/comfyanonymous/ComfyUI.git master
+          git checkout FETCH_HEAD
+
       - name: Update requirements.txt
         working-directory: comfyui
         run: |