enh: fix warning

Co-authored-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Signed-off-by: Andrey Fedorov <fedorov@bwh.harvard.edu>

Author: fedorov

modules/idc_dataset.ipynb

@@ -663,8 +663,8 @@
     ")\n",
     "\n",
     "# Map SEG midpoint z to CT z via world coordinates\n",
-    "seg_mid_world = voxel_to_world(seg_ras.affine, [0, 0, seg_mid_z])\n",
-    "ct_mid_voxel = world_to_voxel(ct_ras.affine, seg_mid_world)\n",
+    "seg_mid_world = voxel_to_world(seg_ras.affine.numpy(), [0, 0, seg_mid_z])\n",
+    "ct_mid_voxel = world_to_voxel(ct_ras.affine.numpy(), seg_mid_world)\n",
     "z_mid = int(np.clip(np.round(ct_mid_voxel[2]), 0, ct_np.shape[2] - 1))\n",
     "\n",
     "# Show which segments are present in the matched slice\n",