Update labeler.yml to v5 syntax

[soheilshahrouz]

Description

Pull Request Labeler v5 was released, introducing new syntax. Since the new syntax is not compatible with v4, triage job fails.

Motivation and Context

To prevent triage job from failing, we need to update labeler.yml file.

How Has This Been Tested?

"infra" label for this PR was automatically added after the bug was fixed.

Types of changes

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

[soheilshahrouz]

@vaughnbetz
When I changed pull_request_target to pull_request, two triage actions are run: one against this branch, and another against master. The one from this branch passes triage, while the one from master fails because it sees the labeler.yml with v4 syntax.

I think if we merge this into master, the problem would be fixed. "infra" label was added to this PR after I replaced pull_request_target with pull_request.

[vaughnbetz]

Thanks! Let me know when CI has gotten far enough that you're confident this can be merged.

[soheilshahrouz]

@vaughnbetz
CI tests triggered by pull requrest are passed. I canceled tests initiated by push, but they should have the same result.
Pull request labeler action triggered by pall_request_target event has failed, but this is not a serious problem as the action is using workflow files from the master branch. The other labeler action that uses workflow files from the current branch was successful.