feat: add support for iOS 15 (#5)

Author: johnnewman-square

Package.swift

@@ -5,7 +5,7 @@ import PackageDescription
 let package = Package(
     name: "KeyboardObserver",
     platforms: [
-        .iOS(.v16),
+        .iOS(.v15),
     ],
     products: [
         .library(

Samples/Tuist/ProjectDescriptionHelpers/Project+KeyboardObserver.swift

@@ -3,7 +3,7 @@ import ProjectDescription
 
 public let keyboardObserverBundleIdPrefix = "com.squareup.keyboard-observer"
 public let keyboardObserverDestinations: ProjectDescription.Destinations = .iOS
-public let keyboardObserverDeploymentTargets: DeploymentTargets = .iOS("16.0")
+public let keyboardObserverDeploymentTargets: DeploymentTargets = .iOS("15.0")
 
 extension Target {
     public static func app(