How to set the z-axis to start from zero?

import plotly.graph_objects as go
fig = go.Figure(data=[
go.Mesh3d(
x=[428568.691308, 428518.006807, 428553.082633, 428482.906996],
y=[872921.737696, 872919.863721, 872855.96713, 872919.65481],
z=[25.168684, 26.955719, 28.512135, 27.591139],

    colorbar_title='z',
    colorscale=[[0, 'gold'],
                [0.5, 'mediumturquoise'],
                [1, 'magenta']],
    intensity=[0, 0.33, 0.66, 1],
    name='y',
    showscale=True,
)

])
fig.show()