Fix componentreflection test (#328)

Fix: this allows component reflection test to pass

Databricks returns an empty string in the REMARKS column rather than a
`NoneType`.

Signed-off-by: Jesse Whitehouse <jesse.whitehouse@databricks.com>

src/databricks/sqlalchemy/_parse.py

@@ -354,7 +354,7 @@ def parse_column_info_from_tgetcolumnsresponse(thrift_resp_row) -> ReflectedColu
         "type": final_col_type,
         "nullable": bool(thrift_resp_row.NULLABLE),
         "default": thrift_resp_row.COLUMN_DEF,
-        "comment": thrift_resp_row.REMARKS,
+        "comment": thrift_resp_row.REMARKS or None,
     }
 
     # TODO: figure out how to return sqlalchemy.interfaces in a way that mypy respects