Enable merge queue (#65)

* Run CI on merge_group events

Enables the aggregating `check` job to run when PRs are queued for merge,
which is required for enabling GitHub's merge queue on `main`.

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Liudmila Molkova <neskazu@gmail.com>

Author: 3 people

.github/workflows/ci.yml

@@ -5,6 +5,8 @@ on:
     branches:
     - 'main'
   pull_request:
+  merge_group:
+    types: [checks_requested]
 
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