Tacked in some maintains to hopefully reduce missed URC's

src/TinyGsmClientBG96.h

@@ -638,6 +638,7 @@ protected:
       return 0;
     }
     // TODO: Wait for ACK? AT+QISEND=id,0
+    maintain();  // look for a very quick response from the remote
     return len;
   }
 
@@ -656,6 +657,7 @@ protected:
     }
     waitResponse();
     DBG("### READ:", len, "from", mux);
+    maintain();  // Listen for a close or other URC
     return len;
   }
 
@@ -672,6 +674,7 @@ protected:
     if (!result) {
       sockets[mux]->sock_connected = modemGetConnected(mux);
     }
+    maintain();  // Listen for a close or other URC
     return result;
   }
 
@@ -690,6 +693,7 @@ protected:
     int res = stream.readStringUntil(',').toInt(); // socket state
 
     waitResponse();
+    maintain();  // Listen for a close or other URC
 
     // 0 Initial, 1 Opening, 2 Connected, 3 Listening, 4 Closing
     return 2 == res;