https://github.com/microsoft/setup-msbuild/blob/master/dist/index.js#L1343

function setOutput(name, value) {
    command_1.issueCommand('set-output', { name }, value);
}

2022-10-12T21:04:43.3430286Z ##[warning]The set-output command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/