Allow to set set axis scaleanchor and scaleratio in template #3499

import plotly.io as pio
import plotly.graph_objects as go

 pio.templates["constrained_axes"] = pio.templates["plotly_white"]
 pio.templates["constrained_axes"].update( go.layout.Template(
    layout_title="constrained_axes",
    layout_xaxis=dict(
        visible = False,
    ),
    layout_yaxis=dict(
        visible = False,
        scaleanchor = 'x',  #
        scaleratio = 1      #  these are currently ignored
    )
))

fig = px.line(df, 
        x="x", 
        y="y", 
        color="color", 
        template="constrained_axes")
fig.show()

fig.update_yaxes(scaleanchor = "x", scaleratio = 1)
fig.show()