ci(Mergify): configuration update

Signed-off-by: ​Andrzej Ressel <[email protected]>

.mergify.yml

@@ -1,19 +1,24 @@
-queue_rules:
-  - name: default
-    conditions: []
-
-pull_request_rules:
-  - name: automatic merge for main when CI passes
-    conditions:
-      - base=main
-      - or:
-          - label=ready-to-merge
-          - label=dependencies
-    actions:
-      queue:
-        name: default
-  - name: delete head branch after merge
-    conditions:
-      - merged
-    actions:
+queue_rules:
+  - name: default
+    merge_method: squash
+    commit_message_template: |
+      {{ title }} (#{{ number }})
+        
+      {{ body }}
+
+pull_request_rules:
+  - name: automatic merge for main when CI passes
+    conditions:
+      - base=main
+      - or:
+          - label=ready-to-merge
+          - label=dependencies
+    actions:
+      queue:
+        name: default
+
+  - name: delete head branch after merge
+    conditions:
+      - merged
+    actions:
       delete_head_branch: