Avoid using the to/from_dask_dataframe dask-cudf API (#1328)

* avoid using to/from_dask_dataframe

* Linting

---------

Co-authored-by: Charles Blackmon-Luca <20627856+charlesbluca@users.noreply.github.com>

Author: rjzamora

dask_sql/input_utils/dask.py

@@ -23,11 +23,10 @@ def to_dc(
     ):
         if gpu:  # pragma: no cover
             try:
-                import dask_cudf
+                import dask_cudf  # noqa: F401
             except ImportError:
                 raise ModuleNotFoundError(
                     "Setting `gpu=True` for table creation requires dask_cudf"
                 )
-            if not isinstance(input_item, dask_cudf.DataFrame):
-                input_item = dask_cudf.from_dask_dataframe(input_item, **kwargs)
+            return input_item.to_backend("cudf", **kwargs)
         return input_item

tests/integration/fixtures.py

@@ -188,7 +188,7 @@ def gpu_datetime_table(datetime_table):
 
 @pytest.fixture()
 def gpu_timeseries(timeseries):
-    return dask_cudf.from_dask_dataframe(timeseries) if dask_cudf else None
+    return timeseries.to_backend("cudf") if dask_cudf else None
 
 
 @pytest.fixture()