Add merge_group trigger to CI workflow

[Copilot]

GitHub merge queues require workflows with required checks to include the merge_group event trigger. Without it, status checks don't run when PRs enter the merge queue, causing merge failures.

Changes

• Added merge_group: trigger to .github/workflows/main.yml alongside existing pull_request and push triggers

The main CI workflow runs unit tests, linting, and integration tests that are required checks for merging.

Other workflows (format.yml, release.yml, stale.yml, label_new_issues.yml) trigger on different events and don't require updates.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Feature]: Triggering merge group checks with GitHub Actions</issue_title>
<issue_description>### Feature summary

Triggering merge group checks with GitHub Actions

Problem statement

You must use the merge_group event to trigger your GitHub Actions workflow when a pull request is added to a merge queue.

Note

If your repository uses GitHub Actions to perform required checks on pull requests in your repository, you need to update the workflows to include the merge_group event as an additional trigger. Otherwise, status checks will not be triggered when you add a pull request to a merge queue. The merge will fail as the required status check will not be reported. The merge_group event is separate from the pull_request and push events.

A workflow that reports a check which is required by the target branch's protections would look like this:

on:
  pull_request:
  merge_group:

</issue_description>

<agent_instructions>We have enabled the merge queue in the repository already: review and update the relevant workflows that might be affected by this configuration change.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Feature]: Triggering merge group checks with GitHub Actions #871

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[sonarqubecloud]

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[gcatanese]

@copilot Should release.yml workflow also be updated?

[Copilot]

@copilot Should release.yml workflow also be updated?

No, release.yml doesn't need the merge_group trigger. It runs on pull_request: types: [closed], which executes after a PR is merged, not during the pre-merge check phase. The merge queue is specifically for running required checks before merging, and release.yml is a post-merge automation for release preparation.