[Auth] Suppress deprecation build warning (#14420)

Author: paulb777

FirebaseAuth/CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 - [changed] Using reCAPTCHA Enterprise and Firebase Auth requires reCAPTCHA
   Enterprise 18.7.0 or later.
+- [fixed] Suppress deprecation build warning introduced in 11.8.0.
 
 # 11.8.0
 - [added] Added `ActionCodeSettings.linkDomain` to customize the Firebase Hosting link domain

FirebaseAuth/Sources/Swift/Backend/RPC/GetOOBConfirmationCodeRequest.swift

@@ -105,6 +105,12 @@ private let kClientType = "clientType"
 /// The key for the "recaptchaVersion" value in the request.
 private let kRecaptchaVersion = "recaptchaVersion"
 
+protocol SuppressWarning {
+  var dynamicLinkDomain: String? { get set }
+}
+
+extension ActionCodeSettings: SuppressWarning {}
+
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 class GetOOBConfirmationCodeRequest: IdentityToolkitRequest, AuthRPCRequest {
   typealias Response = GetOOBConfirmationCodeResponse
@@ -177,7 +183,12 @@ class GetOOBConfirmationCodeRequest: IdentityToolkitRequest, AuthRPCRequest {
     androidMinimumVersion = actionCodeSettings?.androidMinimumVersion
     androidInstallApp = actionCodeSettings?.androidInstallIfNotAvailable ?? false
     handleCodeInApp = actionCodeSettings?.handleCodeInApp ?? false
-    dynamicLinkDomain = actionCodeSettings?.dynamicLinkDomain
+    dynamicLinkDomain =
+      if let actionCodeSettings {
+        (actionCodeSettings as SuppressWarning).dynamicLinkDomain
+      } else {
+        nil
+      }
     linkDomain = actionCodeSettings?.linkDomain
 
     super.init(