tidy broke after vale fix (Ensure linter receives all content before closing stdin commit)

[cpkio]

For some reason tidy (on Windows) didn't like the fix you've done for vale. I had to revert to

    stdin:write('\n', function()
      stdin:shutdown()
      stdin:close()
    end)

and set ignore_exitcode = true to get rid of tidy annoying me with 'exited with code 2' error.

[mfussenegger]

Could you check if this still works after #145 ?