NB this is a PR from samtools/htscodecs itself as a test to see if it then permits the new CI to run as validation. (If not, you can see the results of the CI here anyway.)
Remove AppVeyor (config has gone and temporarily deactivated the execution of it in the repo settings)
Added GitHub Actions workflow for MinGW
Added workflow for linux / macos basic builds, therefore reducing the number of concurrent cirrus-ci jobs needed.
NB this is a PR from samtools/htscodecs itself as a test to see if it then permits the new CI to run as validation. (If not, you can see the results of the CI here anyway.)