Fix mergify rules

Signed-off-by: Chris Doherty <[email protected]>

.github/mergify.yml

@@ -1,22 +1,35 @@
 # The `check-success` should be specifying the final job in the CI workflow assuming it depends
 # directly or indirectly on all other jobs passing.
 
+shared:
+  # Rules applicable to both queueing and merge requests.
+  compulsory: &compulsory
+
+    # Ensure the minimal CI checks have passed.
+    - check-success=DCO
+    - check-success=Package
+
+    # Ensure we're targetting the default branch.
+    - base=main
+
+    # Ensure we have adequete reviews.
+    - "#approved-reviews-by>=1"
+    - "#changes-requested-reviews-by=0"
+
 queue_rules:
   - name: default
     conditions:
-      - check-success=DCO
-      - check-success=package
+      - and: *compulsory
 
 pull_request_rules:
-  - name: Automatic merge on approval
+  - name: Automatic merge
     conditions:
-      - base=main
-      - "#approved-reviews-by>=1"
-      - "#changes-requested-reviews-by=0"
-      - check-success=DCO
-      - check-success=package
+      - and: *compulsory
+
+      # Ensure the review is opted in using labels.
       - label!=do-not-merge
       - label=ready-to-merge
+
     actions:
       queue:
         method: merge