Remove InvalidVersions from Update.newerVersions

[fthomas]

closes #371

[codecov]

Codecov Report

Merging #494 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #494   +/-   ##
=======================================
  Coverage   56.51%   56.51%           
=======================================
  Files          64       64           
  Lines         775      775           
  Branches       31       35    +4     
=======================================
  Hits          438      438           
  Misses        337      337

Impacted Files	Coverage Δ
.../main/scala/org/scalasteward/core/sbt/parser.scala	100% <100%> (ø)	⬆️

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