chore: remove CocoaPods-based example apps

The SDK ships via SPM only from 4.0.0. Drop the UIKit/CocoaPods demos
(AdaptyRecipes-UIKit, OnboardingsDemo-UIKit) and their references in
Examples docs and .gitignore, and remove the CocoaPods/podspec handling
from update_version.sh (also relax its version regex to accept pre-release
suffixes like -beta.1).

Author: x401om

Examples/AdaptyRecipes-SwiftUI/README.md

@@ -1,6 +1,6 @@
 ### AdaptyRecipes-SwiftUI Demo App
 
-AdaptyRecipes-SwiftUI demo app is designed to show you how to work with Paywall Builder paywalls in Adapty. The app have minimal functionality, serving as both a tutorial and an example. The app is built with SwiftUI using Swift Package Manager for dependency management. If you need ademo app built with UIKit using CocoaPods for dependency management, refer to [AdaptyRecipes-UIKit demo app](../AdaptyRecipes-UIKit/README.md).
+AdaptyRecipes-SwiftUI demo app is designed to show you how to work with Paywall Builder paywalls in Adapty. The app have minimal functionality, serving as both a tutorial and an example. The app is built with SwiftUI using Swift Package Manager for dependency management.
 
 The app contains two tabs: