AO3-7341 Add concurrency-key on Automated tests

[onefangg]

Pull Request Checklist

• Have you read "How to write the perfect pull request"?
• Have you read the contributing guidelines?
• Have you added tests for any changed functionality?
  No tests added here, because functionality change is just for developers.
• Have you added the Jira issue number
  as the first thing in your pull request title (e.g. AO3-1234 Fix thing)
• Do you have fewer than 5 pull requests already open? If not, please wait
  until they are reviewed and merged before creating new pull requests.

Issue

https://otwarchive.atlassian.net/browse/AO3-7341

Purpose

What does this PR do?

Cancels previous workflow runs for automated tests, if there is a newer run queued. The concurrency key is added just for automated tests as specified in the ticket, but I could also add it to reviewdog.yml as it also runs on pull_request trigger.

Testing Instructions

After this has been merged to master, PRs that have commits pushed while the automated tests are still running will result in said tests being cancelled. ie. Automated tests will only be ran for the latest commit push, previously queued tasks will be cancelled.

Example of my own testing:

I've created the PR which creating this first test run, then made a cosmetic change to my commit message by running git commit --amend then git push --force-with-lease to force a diff commit hash, resulting in the second test run being queued, which causes the first test run to be cancelled

Credit

Yi Fang (she/her)

[redsummernight]

From this Stack Overflow comment, let's instead use:

${{ github.workflow }}-${{ github.ref || github.run_id }}

github.ref also covers pull requests, and github.run_id is guaranteed to exist on any run.