fix: remove duplicate import and replace type() with isinstance() (sammchardy#1623)

Author: xingarr

binance/__init__.py

@@ -13,7 +13,6 @@
     OptionsDepthCacheManager,  # noqa
     ThreadedDepthCacheManager,  # noqa
     FuturesDepthCacheManager,  # noqa
-    OptionsDepthCacheManager,  # noqa
 )
 from binance.ws.streams import (
     BinanceSocketManager,  # noqa

binance/helpers.py

@@ -76,7 +76,7 @@ def round_step_size(
 def convert_ts_str(ts_str):
     if ts_str is None:
         return ts_str
-    if type(ts_str) == int:
+    if isinstance(ts_str, int):
         return ts_str
     return date_to_milliseconds(ts_str)