Plotly:如何绘制没有填充区域的等高线图？

import plotly.graph_objects as go
import numpy as np

x = np.linspace(-5, 5, 100)
y = np.linspace(-5, 5, 100)
X, Y = np.meshgrid(x, y)
Z = np.sin(np.sqrt(X**2 + Y**2))

fig = go.Figure(data=go.Contour(
    x=x,
    y=y,
    z=Z,
    colorscale='Viridis',
    contours=dict(
        showlabels=False,  # 不显示等高线标签
        labelfont=dict(
            size=12,
            color='white',
        ),
    ),
))

fig.update_layout(
    title='等高线图',
    xaxis=dict(title='X轴'),
    yaxis=dict(title='Y轴'),
    autosize=False,
    width=500,
    height=500,
)

fig.show()