refactor: remove other warnings (#769)

## 📜 Description

Fixed newly discovered warnings.

## 💡 Motivation and Context

In paper example I've seen even more warnings and fixed them as well 🙂
initially these warning were added in
#727

Follow up for
#766

## 📢 Changelog

<!-- High level overview of important changes -->
<!-- For example: fixed status bar manipulation; added new types
declarations; -->
<!-- If your changes don't affect one of platform/language below - then
remove this platform/language -->

### iOS

- fixed 2 warnings in `KeyboardMovementObserver`;

## 🤔 How Has This Been Tested?

Tested manually.

## 📝 Checklist

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

ios/observers/KeyboardMovementObserver.swift

@@ -189,7 +189,7 @@ public class KeyboardMovementObserver: NSObject {
   }
 
   @objc func keyboardWillDisappear(_ notification: Notification) {
-    let (duration, keyboardFrame) = notification.keyboardMetaData()
+    let (duration, _) = notification.keyboardMetaData()
     tag = UIResponder.current.reactViewTag
     self.duration = duration
 
@@ -233,7 +233,7 @@ public class KeyboardMovementObserver: NSObject {
   }
 
   @objc func keyboardDidDisappear(_ notification: Notification) {
-    let (duration, keyboardFrame) = notification.keyboardMetaData()
+    let (duration, _) = notification.keyboardMetaData()
     tag = UIResponder.current.reactViewTag
 
     onCancelAnimation()