Allow arbitrary `Mapping` types when setting properties, rather than only `dict`

Currently, it seems that only dict is allowed when setting properties. It would be better if an arbitrary Mapping type were allowed, since that grants the user the flexibility to control properties with alternative data structures such as a ChainMap.

As far as I can tell, this could be done just by changing the validate_coerce() logic to check isinstance(v, Mapping) instead of isinstance(v, dict), e.g. on this line.

Example

This raises a ValueError:

from collections import ChainMap

import plotly.graph_objects as go


layout = ChainMap(
    dict(width=1000),
    dict(width=500, height=500),
)
go.Figure(layout=layout)

packages/python/plotly/_plotly_utils/basevalidators.py の、issue で参照されている validate_coerce() ロジックから始めてください。Figure(layout=ChainMap(...)) の例がどのように検証されるかを確認し、そのうえで、既存の dict の動作を変更せずに任意の Mapping 入力が受け入れられることを確認してください。