Update Scala, sbt, and sbt plugins

[fthomas]

No description provided.

[LukaJCB]

👍

[ceedubs]

The build is failing with [error] (bench / Compile / compileIncremental) scala.reflect.internal.MissingRequirementError: object java.lang.Object in compiler mirror not found.

I feel like java.lang.Object is something that should probably be there. 🤔

[LukaJCB]

@ceedubs That seems to be an issue in every single build for 2.11, not specific to this PR. No clue what's going on there 😄

[fthomas]

The first error seems to be

[error] error while loading <root>, Error accessing /home/travis/.coursier/cache/v1/https/repo1.maven.org/maven2/org/scalaz/scalaz-core_2.11/7.2.21/scalaz-core_2.11-7.2.21.jar

I tried deleting the build cache but this had no effect. I'll investigate further.

[codecov-io]

Codecov Report

Merging #2260 into master will increase coverage by 0.3%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #2260     +/-   ##
=========================================
+ Coverage   94.66%   94.96%   +0.3%     
=========================================
  Files         333      333             
  Lines        5787     5799     +12     
  Branches      216      218      +2     
=========================================
+ Hits         5478     5507     +29     
+ Misses        309      292     -17

Impacted Files	Coverage Δ
laws/src/main/scala/cats/laws/MonadLaws.scala	100% <0%> (ø)	⬆️
core/src/main/scala/cats/syntax/option.scala	100% <0%> (ø)	⬆️
core/src/main/scala/cats/data/Ior.scala	98.48% <0%> (+0.01%)	⬆️
core/src/main/scala/cats/data/Kleisli.scala	96.93% <0%> (+0.03%)	⬆️
core/src/main/scala/cats/Eval.scala	98.75% <0%> (+0.04%)	⬆️
core/src/main/scala/cats/data/IorT.scala	97.76% <0%> (+0.05%)	⬆️
core/src/main/scala/cats/syntax/either.scala	99.16% <0%> (+14.16%)	⬆️

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[fthomas]

Updating Scalaz to 7.2.23 fixed the problem on 2.11 - but don't ask me why.