run method
Runs this command.
The return value is wrapped in a Future if necessary and returned by
CommandRunner.runCommand.
Implementation
@override
void run() async {
  await initializeObs();
  final sourceScreenshotResponse = await obs.sources.getSourceScreenshot(
    SourceScreenshot(
      sourceName: argResults!['source-name'],
      imageFormat: argResults!['image-format'],
    ),
  );
  print(sourceScreenshotResponse);
  obs.close();
}