glTF impoter: Fix bad check when node id is 0

io_scene_gltf2/blender/imp/gltf2_blender_animation_bone.py

@@ -53,7 +53,7 @@ class BlenderBoneAnim():
                 translation_keyframe = loc_gltf_to_blender(values[idx * 3 + 1])
             else:
                 translation_keyframe = loc_gltf_to_blender(values[idx])
-            if not node.parent:
+            if node.parent is None:
                 parent_mat = Matrix()
             else:
                 if not gltf.data.nodes[node.parent].is_joint: