Release 3.8.1 (plotly#1530)

* Update CHANGELOG and README for 3.8.1
* Update plotlywidget version to 0.9.1

Release 3.8.1 (plotly#1530)

* Update CHANGELOG and README for 3.8.1
* Update plotlywidget version to 0.9.1

Release 3.8.0 (plotly#1518)

* CHANGELOG and README updates
* Bump plotlywidget version
* align hoverlabels left and constant-size legend items in builtin themes (plotly#1520)
* update generated templates
* update widget version to 0.9.0

Release 3.8.0 (plotly#1518)

* CHANGELOG and README updates
* Bump plotlywidget version
* align hoverlabels left and constant-size legend items in builtin themes (plotly#1520)
* update generated templates
* update widget version to 0.9.0

package build

package build

3.7.1 release branch (plotly#1470)

* CHANGELOG
* README version updates
* No change needed to plotlywidget extension

Update README installation versions

Update README installation versions

Release 3.6.1 (plotly#1430)

* Update to plotly.js 1.44.3
* 3.6.1 changelog