Enable optional merge queue for this repo

[terrytangyuan]

See https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/configuring-pull-request-merges/managing-a-merge-queue

[terrytangyuan]

• Check whether merge queue would affect concurrent build cancellation https://github.com/argoproj/argo-workflows/blob/main/.github/workflows/ci-build.yaml#L14

[agilgur5]

For reference, this is a follow-up to yesterday's Contributor Meeting, which itself was a follow-up to #12610 (comment) (and further comments) and two prior Slack discussions

[terrytangyuan]

@agilgur5 Do you know any example repos that have this enabled?

[agilgur5]

Not off the top of my head unfortunately. Been working on this repo primarily for the past bit and merge queues apparently can only be used for repos of an org (and not for personal repos), so I couldn't use my own as examples.

k8s used to have Prow or the k8s bot do this as far as I remember, but some things have changed once GitHub had native features. Bors is the bot that predates the native GH feature, and since it's a bot you can search for its comments (e.g. bors-ng/bors-ng#142).
Merge queues are more similar to the auto-merge feature in that it changes the CI status and leaves a little icon in the PR IIRC, which is not searchable

[agilgur5]

Ah here's a CNCF example: cncf/presentations#186.

Merge queues are more similar to the auto-merge feature in that it changes the CI status and leaves a little icon in the PR IIRC, which is not searchable

See the little icons that say "added this pull request to the merge queue" and "Merged via the queue":

The feature also adds this link: https://github.com/cncf/presentations/queue/main

And you can see the github-merge-queue[bot] in the (relatively new) "Activity" view, where it creates and deletes temporary branches in order to test: https://github.com/cncf/presentations/activity. But it does not itself make comments, so I found that not by searching on GitHub but by a simple "github merge queue cncf" google search, which had crawled the activity view.