fix: iOS 13 compilation issues

[kirillzyusko]

📜 Description

Fixed iOS 13 compatibility.

💡 Motivation and Context

For projects that are targeting iOS 12.4 (for example react-native 0.72) textFieldDidChangeSelection method doesn't exist for UITextFieldDelegate.

To fix it I added @available annotation that takes the method into compilation only for iOS 13+.

Technically it's not very correct solution, because onSelectionChange will not be fired from my handler on iOS 12 - if we want to have this event we have to capture events from setter and forward it, but without subclassing it's pretty hard to achieve (only method swizzling as a last resort). But I don't want to spend too much time right now - if I get request that this functionality must be implemented for iOS 12, then I'll add it (otherwise I don't see a lot of sense in that right now, because RN already dropped minimal supported version, so I expect more and more people will move away from iOS 12 soon).

Closes #459

📢 Changelog

iOS

• added a guard for textFieldDidChangeSelection (iOS 13+);

🤔 How Has This Been Tested?

Tested on CI.

📝 Checklist

• CI successfully passed
• I added new mocks and corresponding unit-tests if library API was changed

[github-actions]

📊 Package size report

Current size	Target Size	Difference
136525 bytes	136510 bytes	15 bytes 📈