make estimate_fee_per_kb as before 7c5ebbf8

electrum/plugins/joinmarket/jm_base_code.py

@@ -136,7 +136,8 @@ class JMBaseCodeMixin:
         tx_fees_factor = abs(self.jmconf.tx_fees_factor)
 
         # NOTE: can not get data from estimatesmartfee with electrum protocol,
-        mempoolminfee_in_sat = None
+        # but value with default config seems 1000 sat/kb
+        mempoolminfee_in_sat = 1000
         # in case of error
         if mempoolminfee_in_sat is None:
             mempoolminfee_in_sat = fallback_fee