Drop merge-mode

Skip-Release-Notes

Change-Id: Ieadf1e805797fcad655b97905dfa2b70c5a51d36
diff --git a/zuul.d/project.yaml b/zuul.d/project.yaml
index f19f0ed..e8fe03e 100644
--- a/zuul.d/project.yaml
+++ b/zuul.d/project.yaml
@@ -13,7 +13,6 @@
 # under the License.
 
 - project:
-    merge-mode: squash-merge
     check:
       jobs:
         - atmosphere-chart-vendor