Support for new version of Xcode and iOS

In the official documentation, it specifically states that iOS-Tagent only works with certain versions of Xcode and iOS, newer versions may not work. I hope that the iOS-Tagent devs can continue to update it in future releases.

However I just want to put a placeholder here to say that I was able to build and install [Appium's WebDriverAgent ](https://github.com/appium/WebDriverAgent)and have Airtest IDE interface with it. Just build and run the `WebDriverAgentRunner` target. So until iOS-Tagent devs fix this issue it can be used as a workaround.

I am new to Airtest so I was only able to confirm that it connects and can execute some simple taps using the IDE. Here are my specifications:

Xcode: 12.5
iOS: 14.5.1

Hope this helps someone!

如果英文看不懂我可以寫中文，謝謝！