[Bug Fix] Modify the deprecated interp2d method into the supported RegularGridInterpolator method

[CloudRipple]

将不受新版本SciPy支持的方法interp2d，修改为受支持的RegularGridInterpolator方法
Modify the method interp2d, which is not supported by the new version of SciPy, into the supported RegularGridInterpolator method.

issue #507

具体修改如下：

    # f = interpolate.interp2d(y, x, height_field_downsampled, kind="linear")
    f = interpolate.RegularGridInterpolator((y, x), height_field_downsampled, method="linear")

    x_upsampled = np.linspace(0, terrain.width * terrain.horizontal_scale, terrain.width)
    y_upsampled = np.linspace(0, terrain.length * terrain.horizontal_scale, terrain.length)
    # z_upsampled = np.rint(f(y_upsampled, x_upsampled))
    z_upsampled = np.rint(f((y_upsampled, x_upsampled)))

[zhenjia-xu]

Thanks for fixing this!

[Kashu7100]

I think we need to add the scipy requirements to pyproject.toml.

[Nate711]

Thanks, I needed this change to make the terrain work with scipy 1.15. I also agree the pyproject.toml should be updated. Although it's a separate issue, open3d also needs to be installed.