Replace sortorder package with new version.

[agnivade]

Refs fvbommel/util#7

[codecov-commenter]

Codecov Report

Merging #48 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #48   +/-   ##
=======================================
  Coverage   64.65%   64.65%           
=======================================
  Files           5        5           
  Lines         365      365           
=======================================
  Hits          236      236           
  Misses         90       90           
  Partials       39       39           

Impacted Files	Coverage Δ
rollup.go	78.82% <ø> (ø)

---

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 50a7a8a...8db5e7b. Read the comment docs.