Update YYTextAsyncLayer.m

[Apolla]

[CHG]fix xcode15 Assertion failure in void _UIGraphicsBeginImageContextWithOptions(CGSize, BOOL, CGFloat, BOOL)(), UIGraphics.m:410

[sukesk]

if(!(self.bounds.size.width*self.bounds.size.height)) return; UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.opaque, self.contentsScale);