Use conditional API requests

[carlobeltrame]

We are using this action and await-remote-run to trigger workflows on 22 other repositories from one repository. We are quickly running into the rate limits of the GitHub API of 5000 requests per hour with a PAT, even when limiting the number of parallel triggered workflows. One of the reasons is that sometimes we need to poll for a long time until the remote workflow starts running, because our available runners are occupied with other workflows (or even with the many waiting and polling workflows in the main repository).

For this reason, I am looking for ways to reduce the number of API requests counting towards our rate limit. One approach offered by GitHub is conditional API requests. The listWorkflowRuns (used in return-dispatch), listJobsForWorkflowRun (used in both actions) and getWorkflowRun (used in await-remote-run) endpoints all return an ETag. We could keep track of the etag of the previous request of the same type, and add an if-none-match header where possible.

If you think this is a good idea, I could work on PRs for both actions.

[Codex-]

I think that sounds very reasonable! I'd highly appreciate any contributions to make this happen

I've been working on a 'refresh' for await-remote-run but it's lagging behind, so if you make any contributions there, I'll ensure those are brought forward to any new versions in progress