feat: add async tracking permission API

GADManager/GADManager.swift

@@ -137,7 +137,7 @@ public class GADManager<E : RawRepresentable> : NSObject, GoogleMobileAds.FullSc
                     print("[\(#function)] Restricted")
                     //show alert
                     //showAlert(title: String, msg: String, actions : [UIAlertAction], style: UIAlertControllerStyle, sourceView: UIView? = nil, sourceRect: CGRect? = nil, popoverDelegate: UIPopoverPresentationControllerDelegate? = nil, completion: (() -> Void)? = nil)
-                    return;
+                    break;
                 @unknown default:
                     print("[\(#function)] Unknown")
                     break;
@@ -146,6 +146,17 @@ public class GADManager<E : RawRepresentable> : NSObject, GoogleMobileAds.FullSc
             completion?(status);
         }
     }
+
+    /// Requests App Tracking Transparency permission asynchronously and returns the resulting authorization status.
+    /// - Returns: The authorization status reported by `ATTrackingManager`.
+    @available(iOS 14, *)
+    public func requestPermissionAsync(viewControllerForAlert viewController: UIViewController? = nil, title: String? = nil, msg: String? = nil, cancel: String? = nil, settings: String? = nil) async -> ATTrackingManager.AuthorizationStatus {
+        await withCheckedContinuation { continuation in
+            requestPermission(viewControllerForAlert: viewController, title: title, msg: msg, cancel: cancel, settings: settings) { status in
+                continuation.resume(returning: status)
+            }
+        }
+    }
     #endif
 
     public func reset(unit: E){

README.md

@@ -126,6 +126,15 @@ if #available(iOS 14, *) {
 }
 ```
 
+With Swift concurrency:
+
+```swift
+if #available(iOS 14, *) {
+    let status = await adManager.requestPermissionAsync()
+    adManager.prepare(interstitialUnit: .interstitial)
+}
+```
+
 ## Delegate
 
 The delegate is responsible for persisting the last-shown time per unit so throttling works correctly across app launches.