mergify: move autosquash to queue_rules (backport #4100)

[mergify]

Describe your changes

replaces #4099

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes
• If this PR requires changes to the docs or specs, a corresponding PR is opened in the namada-docs repo
  • Relevant PR if applies:
• If this PR affects services such as namada-indexer or namada-masp-indexer, a corresponding PR is opened in that repo
  • Relevant PR if applies:

---

This is an automatic backport of pull request #4100 done by [Mergify](https://mergify.com).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.58%. Comparing base (6bd88fc) to head (1784b1e).
Report is 4 commits behind head on maint-0.46.

Additional details and impacted files

@@             Coverage Diff             @@
##           maint-0.46    #4114   +/-   ##
===========================================
  Coverage       74.58%   74.58%           
===========================================
  Files             341      341           
  Lines          107484   107484           
===========================================
+ Hits            80166    80169    +3     
+ Misses          27318    27315    -3     

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