[v1.7.0][Bug] Fix Voxel Editor error with "voxel_editor.py"

[jim19930609]

Reproduce

cd voxel_editor
python3 voxel_editor.py

Log

Traceback (most recent call last):
  File "/home/taichigraphics/workspace/TaichiRepos/Release/voxel_editor/voxel_editor.py", line 329, in <module>
    main()
  File "/home/taichigraphics/workspace/TaichiRepos/Release/voxel_editor/voxel_editor.py", line 322, in main
    renderer.accumulate()
  File "/home/taichigraphics/workspace/TaichiRepos/Release/voxel_editor/renderer.py", line 438, in accumulate
    self.render()
  File "/home/taichigraphics/workspace/TaichiRepos/Release/taichi/python/taichi/lang/kernel_impl.py", line 1168, in __call__
    raise type(e)("\n" + str(e)) from None
taichi.lang.exception.TaichiCompilationError: 
File "/home/taichigraphics/workspace/TaichiRepos/Release/voxel_editor/renderer.py", line 327, in render:
        ti.block_dim(256)
        ^^^^^^^^^^^^
Traceback (most recent call last):
  File "/home/taichigraphics/workspace/TaichiRepos/Release/taichi/python/taichi/lang/ast/ast_transformer_utils.py", line 27, in __call__
    return method(ctx, node)
  File "/home/taichigraphics/workspace/TaichiRepos/Release/taichi/python/taichi/lang/ast/ast_transformer.py", line 1040, in build_Attribute
    node.ptr = getattr(node.value.ptr, node.attr)
  File "/home/taichigraphics/workspace/TaichiRepos/Release/taichi/python/taichi/__init__.py", line 23, in __getattr__
    raise AttributeError(f"module '{__name__}' has no attribute '{attr}'")
AttributeError: module 'taichi' has no attribute 'block_dim'