GitHub Actions: replace set-output calls
GitHub Actions: replace set-output calls

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/

brechtm/rinohtype,brechtm/rinohtype,brechtm/rinohtype