Do we need .travis+appveyor in nim repo now that we have azure-pipelines? can we remove these?
This leads to odd cases where PR's are green but nim's build is broken, since nim's build (triggered on PR merge IIUC) runs on travis+appveyor (at least) but PR's run azure-pipelines (+freebsd buildsh.rt) Keeping travis/appveyor creates additional maintenance burden, and IIUC they don't add anything compared to what's already tested via azure-pipelines + builldsh.rt
