If I'm reading https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing correctly, Mac builds are moving out of TravisCI's free tier. We'd either need to pay to continue building them ($15 for 500 minutes of build time) or move to a different system.
AppVeyor, which is used for the Windows build, does offer Mac machines and is still free, at least at the moment. There were some blockers in premake (see https://github.com/mrichards42/xword/issues/40#issuecomment-598001963) which might have been fixed by now. That's probably the lowest friction thing to try since we use it for Windows already.
GitHub Actions might be another option (which is perhaps more likely to last longer since it's backed by Microsoft/GitHub) if that doesn't work out.
If I'm reading https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing correctly, Mac builds are moving out of TravisCI's free tier. We'd either need to pay to continue building them ($15 for 500 minutes of build time) or move to a different system.
AppVeyor, which is used for the Windows build, does offer Mac machines and is still free, at least at the moment. There were some blockers in premake (see https://github.com/mrichards42/xword/issues/40#issuecomment-598001963) which might have been fixed by now. That's probably the lowest friction thing to try since we use it for Windows already.
GitHub Actions might be another option (which is perhaps more likely to last longer since it's backed by Microsoft/GitHub) if that doesn't work out.