v2.1.0

Added

• Add icicle trace type [#5546]
  with thanks to @Kully and @mtwichan of Zyphr for their contribution!
• Implement legendrank attribute in traces [#5591]
• Implement fgopacity, fgcolor & "overlay" fillmode for bars and
  handle bar pattern and legend when marker.colorscale is present [#5733]

Changed

• Replace deprecated node-sass modules with Sass and update plot CSS [#5729]
• Bump probe-image-size to v7.2.1 [#5739]
• More maintenance work listed under the v2.1.0 milestone

Fixed

• Fix setting the width of categorical bars & boxes to unit [#5732]