ci(Mergify): configuration update

Signed-off-by: Renato Barucco <[email protected]>

.mergify.yml

@@ -1,8 +1,19 @@
-pull_request_rules:
-  - name: "Automatic merge when CI passes and approved"
-    conditions:
-      - "author=dependabot[bot]"
-      - "check-success=dependency-review"
-    actions:
-      merge:
+pull_request_rules:
+  - name: Label conflicting pull requests
+    description: Add a label to a pull request with conflict to spot it easily
+    conditions:
+      - conflict
+    actions:
+      comment:
+        message: '@{{author}} this pull request is now in conflict 😩'
+      label:
+        toggle:
+          - conflict
+
+  - name: Automatic merge when CI passes and approved
+    conditions:
+      - author=dependabot[bot]
+      - check-success=dependency-review
+    actions:
+      merge:
         method: merge