Update greetings.yml (ultralytics#4856)

.github/workflows/greetings.yml

@@ -18,7 +18,7 @@ jobs:
             git remote add upstream https://github.com/ultralytics/yolov5.git
             git fetch upstream
             git checkout feature  # <----- replace 'feature' with local branch name
-            git rebase upstream/master
+            git merge upstream/master
             git push -u origin -f
             ```
             - ✅ Verify all Continuous Integration (CI) **checks are passing**.