Upgrade to sbt 1.3.0-RC5

[xerial]

• This version includes a fix for slow publishing to Sonatype NEXUS Flip the default to not use Gigahorse by default  sbt/librarymanagement#317

[codecov]

Codecov Report

Merging #647 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #647   +/-   ##
=======================================
  Coverage   81.98%   81.98%           
=======================================
  Files         239      239           
  Lines        8743     8743           
  Branches      685      685           
=======================================
  Hits         7168     7168           
  Misses       1575     1575

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