Update sbt to 1.3.13

[scala-steward]

Updates org.scala-sbt:sbt from 1.3.12 to 1.3.13.
GitHub Release Notes - Version Diff

I'll automatically update this PR to resolve conflicts as long as you don't change it yourself.

If you'd like to skip this version, you can just close this PR. If you have any feedback, just mention me in the comments below.

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Have a fantastic day writing Scala!

Ignore future updates

Add this to your .scala-steward.conf file to ignore future updates of this dependency:

updates.ignore = [ { groupId = "org.scala-sbt", artifactId = "sbt" } ]

labels: library-update, semver-patch

[codecov]

Codecov Report

Merging #521 into master will decrease coverage by 11.97%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master     #521       +/-   ##
===========================================
- Coverage   90.45%   78.47%   -11.98%     
===========================================
  Files          24       24               
  Lines         618      618               
  Branches        1        1               
===========================================
- Hits          559      485       -74     
- Misses         59      133       +74     

Impacted Files	Coverage Δ
github4s/src/main/scala/github4s/Github.scala	0.00% <0.00%> (-100.00%)	⬇️
...ithub4s/src/main/scala/github4s/GithubConfig.scala	0.00% <0.00%> (-100.00%)	⬇️
...4s/src/main/scala/github4s/http/Http4sSyntax.scala	0.00% <0.00%> (-100.00%)	⬇️
...s/src/main/scala/github4s/domain/PullRequest.scala	0.00% <0.00%> (-100.00%)	⬇️
...s/src/main/scala/github4s/modules/GithubAPIs.scala	0.00% <0.00%> (-100.00%)	⬇️
.../src/main/scala/github4s/http/RequestBuilder.scala	0.00% <0.00%> (-100.00%)	⬇️
...ub4s/src/main/scala/github4s/http/HttpClient.scala	16.66% <0.00%> (-70.84%)	⬇️
.../scala/github4s/interpreters/AuthInterpreter.scala	60.00% <0.00%> (-40.00%)	⬇️
github4s/src/main/scala/github4s/Decoders.scala	84.32% <0.00%> (-6.72%)	⬇️

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