Allow to actually disable refresh interval

[dragoon]

Current implementation of refresh interval doesn't work correct according to the library documentation -- setting the refresh_interval argument to 0 or None will actually set it to default value (30 minutes). My fix doesn't change the behavior as advertised, it will set refresh_interval to default when not specified, and disabled when 0 or None is passed.

[dragoon]

related https://github.com/sammchardy/python-binance/issues/1365

[sammchardy]

Thanks @dragoon