Fix PEP8 unused import

Author: bnaul

pandas/tests/dtypes/test_inference.py

@@ -20,7 +20,7 @@
                     DatetimeIndex, TimedeltaIndex, Timestamp,
                     Panel, Period, Categorical, isna, Interval,
                     DateOffset)
-from pandas.compat import u, PY2, PY3, StringIO, lrange
+from pandas.compat import u, PY2, StringIO, lrange
 from pandas.core.dtypes import inference
 from pandas.core.dtypes.common import (
     is_timedelta64_dtype,