enable color by timedelta in Plotly Express

When you domain is time series data, you sooner or later have to plot data of the Timedelta type. It would be nice to be able to understand what I am looking at when plotting, and coloring by, such data, which is hard when it is interpreted as an int in both hover text and color bar tick text.

Similar to #2450, but covering the timedelta data type, rather than datetime.

See also #799 and #801 for similar requests for the x and y axes.

首先查看 #2450 中相关的 datetime 请求，以及 #799 和 #801 中类似的坐标轴请求，然后跟踪 Plotly Express 如何处理用于悬停文本和颜色刻度的 Timedelta 值。完成的标准是：timedelta 颜色值在悬停文本和颜色条刻度标签中以有意义的形式呈现，而不是显示为整数。