HTML entities no longer render in ticktext

[cpsievert]

Introduced in 1.28.0 release

https://codepen.io/cpsievert/pen/ZyJoPW

[etpinard]

Thanks for the report. Caused by #1792. I can't believe no test failed to catch this.

[etpinard]

cc @alexcjohnson

[etpinard]

Here's the list of entities we should support:

https://github.com/plotly/plotly.js/blob/master/src/constants/string_mappings.js