chore(oracle): clean up converter

ibis/backends/oracle/converter.py

@@ -1,14 +1,9 @@
 from __future__ import annotations
 
 import datetime
-from typing import TYPE_CHECKING
 
 from ibis.formats.pandas import PandasData
 
-if TYPE_CHECKING:
-    import ibis.expr.datatypes as dt
-    from ibis.expr.schema import Schema
-
 
 class OraclePandasData(PandasData):
     @classmethod