Require higher version of plotly.js for latest release

[nealpatel645]

When installing the latest version (2.6.0), it installs version 2.14.0 of plotly.js which has an indirect vulnerability: plotly/plotly.js#6333

It looks like even latest version of plotly.js still uses d3-interpolate which depends on vulnerable d3-color.

[camdecoster]

Closed by #360.