ip-checker: the list of IPs returned by the GH API may be out-of-sync

[deniak]

I just learned from the GH support that the list of IPs provided by the API gets updated once a week.
https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#ip-addresses

This could lead to requests being rejected because the IP used by the workflow isn't listed yet.

The support suggests to look at https://www.microsoft.com/en-us/download/details.aspx?id=56519 for a more up-to-date list.

See also w3c/webcodecs#261