Memory Leak Issue Due to Retain Cycles in onButtonClicked, onActionButtonClicked, and onTextChanged

[NnStudio8]

Issue Description:
I've noticed that the SwiftAlertView object is not getting deallocated properly due to strong reference cycles. Specifically, the onButtonClicked, onActionButtonClicked, and onTextChanged closure properties are causing a memory leak by retaining self strongly.

Suggested Fix:
To break the strong reference cycle, I've used [unowned self] in the closure. Here's how I've modified the code to fix the memory leak issue:

// handle events
@discardableResult
public func onButtonClicked(_ handler: @escaping (_ alertView: SwiftAlertView, _ buttonIndex: Int) -> Void) -> SwiftAlertView {
    self.onButtonClicked = { [unowned self] index in
        handler(self, index)
    }
    return self
}

@discardableResult
public func onActionButtonClicked(_ handler: @escaping (_ alertView: SwiftAlertView, _ buttonIndex: Int) -> Void) -> SwiftAlertView {
    self.onActionButtonClicked = { [unowned self] index in
        handler(self, index)
    }
    return self
}

@discardableResult
public func onTextChanged(_ handler: @escaping (_ alertView: SwiftAlertView, _ text: String?, _ textFieldIndex: Int) -> Void) -> SwiftAlertView {
    self.onTextChanged = { [unowned self] text, index in
        handler(self, text, index)
    }
    return self
}

I hope this helps to resolve the issue. Looking forward to your feedback.