Fix stop command on VMB1BL / VMB2BL covers (#73)

* Add support for VMB8PB

* Black code formatting

* Fixed cover off message for VMB1BL/VMB2BL

Author: bdewitte123

velbus/messages/cover_off.py

@@ -106,7 +106,7 @@ def data_to_binary(self):
         else:
             tmp = 0x0C
 
-        return bytes([COMMAND_CODE, tmp]) + struct.pack(">L", self.delay_time)[-3:]
+        return bytes([COMMAND_CODE, tmp])
 
 
 register_command(COMMAND_CODE, CoverOffMessage2, "VMB1BL")