fix rbf parameter in paytomany API (follow-up e1dc7d1e6f)

electrum/commands.py

@@ -703,7 +703,7 @@ class Commands:
 
     @command('wp')
     async def paytomany(self, outputs, fee=None, feerate=None, from_addr=None, from_coins=None, change_addr=None,
-                        nocheck=False, unsigned=False, rbf=None, password=None, locktime=None, addtransaction=False, wallet: Abstract_Wallet = None):
+                        nocheck=False, unsigned=False, rbf=True, password=None, locktime=None, addtransaction=False, wallet: Abstract_Wallet = None):
         """Create a multi-output transaction. """
         self.nocheck = nocheck
         tx_fee = satoshis(fee)