Lately we had a few times that people pushed to their PR branch
a few times to make small changes. Sadly, this triggers all CIs
every time, which takes ~20 minutes. As we are limited in the
amount of runners we get assigned to us, this means all other CI,
even for other repositories within OpenTTD, are delayed too.
We can avoid this by simply cancelling old runs when a new PR is
pushed. There is a downside: sometimes people already push a new
commit, but still want to know if the old one passed. That will
no longer be possible with this change.
This requires the use of WinHTTP (for Windows) or libcurl (for all
others except Emscripten). Emscripten does not support http(s)
calls currently.
On Linux it requires ca-certificates to be installed, so the HTTPS
certificate can be validated. It is really likely this is installed
on any modern machine, as most connections these days are HTTPS.
(On MacOS and Windows the certificate store is filled by default)
Reminder: in case the http(s):// connection cannot be established,
OpenTTD falls back to a custom TCP-based connection to fetch the
content from the content-service. Emscripten will always do this.
