macOS: is damaged and can’t be opened

Hi 👋. 
Very cool idea!  
But there is an inconvenience when using it on macOS. If you just download and install, the application does not open.

## Screenshot

<img width="372" alt="image" src="https://user-images.githubusercontent.com/13949080/168416035-21117a62-3afd-4428-9284-613b23c580a2.png">

## Fix 
```shell
> xattr -cr /Applications/DiffCast.app
```
