Though cURL has served me well since I launched Check Run Reporter, shelling out to bash can be tedious in CI systems with complex DSLs. I've added plugins for CI systems to make working with them more natural. Custom CI tools also let me do things like build in retries and set variables automatically from the build environment.
Since I use Buildkite myself, it was naturally the first integration I wrote. Head on over to the plugin's GitHub repo for instructions.
Check out the repository for instructions. Note that GitHub Action run and uses steps have different working directories (since uses steps get mounted into a docker container), so you may need to experiment a bit to set the correct CHECK_RUN_REPORTER_ROOT value.