Release 0.21.0

[juanpedromoreno]

Apart from the library updates, this release:

• Removes Scala 2.11 support
• Adds Scala 2.13 support
• Removes scalajs support

[codecov]

Codecov Report

Merging #312 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #312   +/-   ##
=======================================
  Coverage   87.85%   87.85%           
=======================================
  Files          37       37           
  Lines         700      700           
  Branches        5        5           
=======================================
  Hits          615      615           
  Misses         85       85

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5d20a44...2a750a2. Read the comment docs.