fix: android custom tabs dismiss callback called before deeplink

Author: nattb8

Plugins/Android/ImmutableAndroid/ImmutableAndroid/src/main/java/com/immutable/unity/ImmutableActivity.java

@@ -102,12 +102,11 @@ public void onNavigationEvent(int navigationEvent, @Nullable Bundle extras) {
                     // set to null before the SDK can use it to notify the consumer of the PKCE result.
                     // See PassportImpl.OnLoginPKCEDismissed and PassportImpl.OnDeepLinkActivated
                     final Handler handler = new Handler(Looper.getMainLooper());
-                    handler.postDelayed(new Runnable() {
-                        @Override
-                        public void run() {
+                    handler.postDelayed(() -> {
+                        if (uri != null) {
                             callbackInstance.onCustomTabsDismissed(uri.toString());
                         }
-                    }, 1000);
+                    }, 2500);
                 }
             }
         });