feat(tvOS): bump min. deployment target to 15.1 (#2863)

## Description

15.1 is the lowest supported version from `[email protected]`
onwards.

https://github.com/react-native-tvos/react-native-tvos?tab=readme-ov-file#general-support-for-tv

## Changes

- **Bump deployment target for tvOS to 15.1**

## Test code and steps to reproduce

N/A

This should not affect the users, unless they're not applying to our
compatibility matrix.

## 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

Author: kkafar

RNScreens.podspec

@@ -4,6 +4,8 @@ package = JSON.parse(File.read(File.join(__dir__, "package.json")))
 
 new_arch_enabled = ENV['RCT_NEW_ARCH_ENABLED'] == '1'
 min_supported_ios_version = new_arch_enabled ? "15.1" : "15.1"
+min_supported_tvos_version = "15.1"
+min_supported_visionos_version = "1.0"
 source_files = new_arch_enabled ? 'ios/**/*.{h,m,mm,cpp}' : ["ios/**/*.{h,m,mm}", "cpp/RNScreensTurboModule.cpp", "cpp/RNScreensTurboModule.h"]
 
 Pod::Spec.new do |s|
@@ -16,7 +18,7 @@ Pod::Spec.new do |s|
   s.homepage     = "https://github.com/software-mansion/react-native-screens"
   s.license      = "MIT"
   s.author       = { "author" => "[email protected]" }
-  s.platforms    = { :ios => min_supported_ios_version, :tvos => "11.0", :visionos => "1.0" }
+  s.platforms    = { :ios => min_supported_ios_version, :tvos => min_supported_tvos_version, :visionos => min_supported_visionos_version }
   s.source       = { :git => "https://github.com/software-mansion/react-native-screens.git", :tag => "#{s.version}" }
   s.source_files = source_files
   s.project_header_files = "cpp/**/*.h" # Don't expose C++ headers publicly to allow importing framework into Swift files