Fix stale _graphdef import paths after subpackage rename

Update two references that still used _graphdef instead of _graph_def
after the subpackage split.

Made-with: Cursor

Author: Andy-Jost

cuda_core/cuda/core/_graph/_graph_builder.pyx

@@ -793,12 +793,12 @@ class Graph:
 
         Parameters
         ----------
-        source : :obj:`~_graph.GraphBuilder` or :obj:`~_graph._graphdef.GraphDef`
+        source : :obj:`~_graph.GraphBuilder` or :obj:`~_graph._graph_def.GraphDef`
             The graph definition to update from. A GraphBuilder must have
             finished building.
 
         """
-        from cuda.core._graph._graphdef import GraphDef
+        from cuda.core._graph._graph_def import GraphDef
 
         cdef cydriver.CUgraph cu_graph
         cdef cydriver.CUgraphExec cu_exec = <cydriver.CUgraphExec><intptr_t>int(self._mnff.graph)

cuda_core/tests/graph/test_graph_update.py

@@ -8,7 +8,7 @@
 from helpers.graph_kernels import compile_common_kernels, compile_conditional_kernels
 
 from cuda.core import Device, LaunchConfig, LegacyPinnedMemoryResource, launch
-from cuda.core._graph._graphdef import GraphDef
+from cuda.core._graph._graph_def import GraphDef
 from cuda.core._utils.cuda_utils import CUDAError