Add another testnet rpc node

Author: benalleng

lib/core/utils/constants.dart

@@ -85,6 +85,7 @@ class ApiServiceConstants {
   // BB test currently not operational
   static const bbElectrumTestUrl = 'ssl://wes.bullbitcoin.com:60002';
   static const publicElectrumTestUrl = 'ssl://blockstream.info:993';
+  static const publicElectrumTestUrlTwo = 'ssl://testnet.aranguren.org:51002';
 
   // Liquid Electrum servers - lwk does not accept ssl:// prefix
   static const bbLiquidElectrumUrlPath = 'les.bullbitcoin.com:995';