[Auth] Synchronize 'TOTPSecret.openInOTPApp(withQRCodeURL:)' to main actor

Author: morganchen12

FirebaseAuth/Sources/Swift/MultiFactor/TOTP/TOTPSecret.swift

@@ -54,7 +54,7 @@ import Foundation
     ///
     /// See more details
     /// [here](https://developer.apple.com/documentation/authenticationservices/securing_logins_with_icloud_keychain_verification_codes)
-    @objc(openInOTPAppWithQRCodeURL:)
+    @MainActor @objc(openInOTPAppWithQRCodeURL:)
     open func openInOTPApp(withQRCodeURL qrCodeURL: String) {
       if GULAppEnvironmentUtil.isAppExtension() {
         // iOS App extensions should not call [UIApplication sharedApplication], even if