#25447 [scala-sttp4-jsoniter] bump Scala to 3.3.9, sttp to 4.0.27, jsoniter-scala to 2.42.0

[scala-sttp4-jsoniter] bump Scala to 3.3.9, sttp to 4.0.27, jsoniter-scala to 2.42.0

• Scala 3.3.8 -> 3.3.9 in the generated build.sbt
• sttp client 4.0.26 -> 4.0.27 (sttpClientVersion option default)
• jsoniter-scala 2.40.1 -> 2.42.0 (jsoniterVersion option default, applied to the generated build.sbt's core/macros/circe artifacts)
• sbt 1.13.0 -> 1.13.1 in the generated project's build.properties
• sbt-scalafmt 2.5.6 -> 2.6.2 and scalafmt 3.10.6 -> 3.11.5
• scalafmt runner.dialect scala213 -> scala3, since the generated code is Scala 3 and the scala213 dialect could not parse it
• use the Scala 3 vararg splice xs* instead of xs: _* in api.mustache

sttp stays on the 4.0.x line: 4.1.0 is built with Scala 3.9 and cannot be consumed from Scala 3.3 LTS. Docs and the petstore sample updated to match.

PR checklist

• Read the contribution guidelines.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

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Summary by cubic

Bumps the dependency defaults and generated project versions for the scala-sttp4-jsoniter client, and updates generated code to Scala 3 vararg syntax.

• Scala bumps: 3.3.8 → 3.3.9, sttp 4.0.26 → 4.0.27, jsoniter-scala 2.40.1 → 2.42.0, sbt 1.13.0 → 1.13.1, sbt-scalafmt 2.5.6 → 2.6.2, scalafmt 3.10.6 → 3.11.5.
• The scalafmt runner dialect switches from scala213 to scala3; the old dialect could not parse the generated Scala 3 code.
• Generated query params now use the Scala 3 vararg splice xs* instead of the removed Scala 2 syntax xs: _*.
• sttp stays on 4.0.x: 4.1.0 is built with Scala 3.9 and cannot be consumed from Scala 3.3 LTS.
• Docs and the petstore sample are updated to match the new defaults.