ci(mergify): upgrade configuration to current format

.mergify.yml

@@ -1,57 +1,57 @@
 queue_rules:
-  - name: default
-    conditions:
-      # Conditions to get out of the queue (= merged)
+  - name: duplicated default from Merge dependency-update PRs
+    queue_conditions:
+      - base=master
+      - label=dependencies
       - check-success~=build \(2\.12\.\d+\)
       - check-success~=build \(2\.13\.\d+\)
       - check-success~=build \(3\.\d+\.\d+\)
-
-pull_request_rules:
-  - name: Label Scala Steward PRs
-    conditions:
-      - author=scala-steward
-    actions:
-      label:
-        add: [dependencies, scala]
-
-  - name: Merge dependency-update PRs
-    conditions:
-      - base=master
-      - label=dependencies
+    merge_conditions:
+      # Conditions to get out of the queue (= merged)
       - check-success~=build \(2\.12\.\d+\)
       - check-success~=build \(2\.13\.\d+\)
       - check-success~=build \(3\.\d+\.\d+\)
-    actions:
-      queue:
-        name: default
-        method: squash
-
-
-  - name: Merge PRs (rebase) which are ready to merge
-    conditions:
+    merge_method: squash
+  - name: duplicated default from Merge PRs (rebase) which are ready to merge
+    queue_conditions:
       - label=ready-to-merge-rebase
       - base=master
       - check-success~=build \(2\.12\.\d+\)
       - check-success~=build \(2\.13\.\d+\)
       - check-success~=build \(3\.\d+\.\d+\)
       - "#review-requested=0"
       - "#changes-requested-reviews-by=0"
-    actions:
-      queue:
-        name: default
-        method: rebase
-
-
-  - name: Merge PRs (squash) which are ready to merge
-    conditions:
+    merge_conditions:
+      # Conditions to get out of the queue (= merged)
+      - check-success~=build \(2\.12\.\d+\)
+      - check-success~=build \(2\.13\.\d+\)
+      - check-success~=build \(3\.\d+\.\d+\)
+    merge_method: rebase
+  - name: duplicated default from Merge PRs (squash) which are ready to merge
+    queue_conditions:
       - label=ready-to-merge-squash
       - base=master
       - check-success~=build \(2\.12\.\d+\)
       - check-success~=build \(2\.13\.\d+\)
       - check-success~=build \(3\.\d+\.\d+\)
       - "#review-requested=0"
       - "#changes-requested-reviews-by=0"
+    merge_conditions:
+      # Conditions to get out of the queue (= merged)
+      - check-success~=build \(2\.12\.\d+\)
+      - check-success~=build \(2\.13\.\d+\)
+      - check-success~=build \(3\.\d+\.\d+\)
+    merge_method: squash
+
+pull_request_rules:
+  - name: Label Scala Steward PRs
+    conditions:
+      - author=scala-steward
+    actions:
+      label:
+        add: [dependencies, scala]
+  - name: Merge PRs (rebase) which are ready to merge + Merge PRs (squash) which are
+      ready to merge + Merge dependency-update PRs
+    conditions: []
     actions:
       queue:
-        name: default
-        method: squash