fix: react-native-screens not building on visionOS (#2210)

## Description

This PR fixes React Native screens not building on visionOS. As this
platform needs explicit imports for used modules

## Changes

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overview, if change is simple you can omit this section.

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- Updated `about.md` docs

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- Fixed building `RNSConvert.h` for visionOS

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## Test code and steps to reproduce

Compile on visionOS

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## Checklist

- [ ] Included code example that can be used to test this change
- [ ] Updated TS types
- [ ] Updated documentation: <!-- For adding new props to native-stack
-->
- [ ]
https://github.com/software-mansion/react-native-screens/blob/main/guides/GUIDE_FOR_LIBRARY_AUTHORS.md
- [ ]
https://github.com/software-mansion/react-native-screens/blob/main/native-stack/README.md
- [ ]
https://github.com/software-mansion/react-native-screens/blob/main/src/types.tsx
- [ ]
https://github.com/software-mansion/react-native-screens/blob/main/src/native-stack/types.tsx
- [ ] Ensured that CI passes

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Co-authored-by: Kacper Kafara <kacperkafara@gmail.com>

ios/RNSConvert.h

@@ -1,4 +1,5 @@
 #ifdef RCT_NEW_ARCH_ENABLED
+#import <UIKit/UIKit.h>
 #import <react/renderer/components/rnscreens/Props.h>
 #import "RNSEnums.h"