remove the error "Can't find class for html:io.keikai.model.impl.html.HtmlExporterFactory"

Steps to Reproduce

public class Keikai517Composer extends SelectorComposer {
    @Override
    public void doAfterCompose(Component comp) throws Exception {
        super.doAfterCompose(comp);
        Exporter exporter = Exporters.getExporter();
    }
}

Current Result

2021-12-10 18:00:18 [WARN ] SExporters:55 - Can't find class for html:io.keikai.model.impl.html.HtmlExporterFactory

Expected Result

no warning

Debug Information

• since keikai-html is deprecated, don't show this error message by default to avoid confusion.