ci(mergify): upgrade configuration to current format (#4805)

Hey there! 👋

We've noticed that your Mergify configuration is using some deprecated
fields.

No worries—we've got your back! This automated PR updates your config to
align with the newest standards, ensuring everything keeps running
smoothly.

Do not procrastinate! You **must upgrade** your configuration before
**2025-06-30**, otherwise your configuration will stop working.

## What's Changed?

- The implicit priority for the queue rules, that was based on their
order, is going to be removed in favor of using `priority_rules`.
This transformation aim to create priority rules, based on your existing
queue rules, in order to keep the same priorities. If this priority
change is not needed for you, you should not close this pull request
until the deadline, otherwise it will be re-created again. (deadline:
2025-06-30)

## Why This Matters

Keeping your configuration up-to-date means you'll benefit from the
latest features and improvements Mergify has to offer. Plus, it helps
prevent any unexpected hiccups down the road.

## Got Questions? We've Got Answers! 🙌

**Is this update safe to merge?**

Absolutely! We've made sure the changes are compatible with your current
setup. Your workflows should continue to work just as before—if not
better!

**Do I need to do anything special after merging?**

Nope! Just merge this PR, and you're all set. If you have any custom
configurations, it's a good idea to give them a quick look to ensure
everything's in order.

**What if I run into issues or have concerns?**

We're here to help! Feel free to [reach out to our support
team](mailto:[email protected]) anytime.

Thanks for being awesome and keeping your configuration up-to-date! If
you have any thoughts or need a hand, don't hesitate to let us know.

Happy merging! 🎉

Co-authored-by: Mergify <37929162+mergify[bot]@users.noreply.github.com>

Author: mergify[bot]

.mergify/config.yml

@@ -133,3 +133,8 @@ pull_request_rules:
           [Conventional Commits]: https://www.conventionalcommits.org
     conditions:
       - status-failure=Validate PR Title
+priority_rules:
+  - name: priority for queue `default-squash`
+    conditions:
+      - queue-name=default-squash
+    priority: 2250