Use 'smart+fasttrack' Mergify merge method to reduce time spent in CI when multiple PRs are in the queue to be merged

Author: marco-c

.mergify.yml

@@ -10,6 +10,7 @@ pull_request_rules:
     actions:
       merge:
         method: squash
+        strict: smart+fasttrack
 
   - name: Automatic merge on approval for contributors
     conditions:
@@ -21,3 +22,4 @@ pull_request_rules:
     actions:
       merge:
         method: squash
+        strict: smart+fasttrack