Description
In plotly.js 1.43.0 the layout.title attribute is now a container that contains sub-attributes like text, font, xanchor, etc. The old behavior of specifying layout.title as a string and using layout.titlefont as the font container is deprecated.
Plotly.py should at least support setting layout.title as a string and setting layout.titlefont but internally map these properties to the new version.
E.g. fig.layout.title = 'A Title' is internally converted to fig.layout.title.text = 'A Title'.
Similarly, fig.layout.titlefont.family = 'Courier' is internally converted to fig.layout.title.font.family = 'Courier'.
Looks like axis titles like fig.layout.xaxis.title have also been converted into containers.
In all cases, a DeprecationWarning should be raised.