build: cross-publish plugin for sbt 1 and sbt 2

[reynaldjoabet]

Enable cross-building so the plugin publishes against both
sbt 1.x (Scala 2.12) and sbt 2.x (Scala 3), and align the CI/
release workflows with sbt 2's JDK 17 requirement.

build.sbt:

• crossScalaVersions := Seq(2.12.20, 3.8.4)
• set bytecode floors via -release (2.12 -> 11, Scala 3 -> 17)
• sbt 2.x target 2.0.0-RC12 -> 2.0.0
• sbt 1.x target / build sbt 1.12.10 -> 1.12.11
• bump Scala 3 3.7.2 -> 3.8.4

CI:

• release & build workflows: Java 8/11 -> 17 (sbt 2 needs 17+)
• update checkout@v6 / setup-java@v5
• build step runs +test +scripted across both Scala axes

---

Summary by cubic

Cross-publish the sbt-openapi-generator plugin for sbt 1.x (Scala 2.12) and sbt 2.x (Scala 3). Align CI and bytecode targets with sbt 2’s JDK 17 requirements.

• Build & CI
  • Enable cross build: crossScalaVersions := Seq(2.12.20, 3.8.4)
  • Set bytecode targets via -release: 11 (Scala 2.12), 17 (Scala 3)
  • Version bumps: sbt 2 target → 2.0.0, Scala 3 → 3.8.4, sbt 1 build → 1.12.11
  • CI: Java 17, actions/checkout@v6, actions/setup-java@v5, run sbt +test +scripted across both Scala axes

^{Written for commit 0af8571. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files

_{Re-trigger cubic}

[wing328]

thanks for the PR

we will include it in the next stable release

[ags313]

Is there an ETA? Would love to upgrade to sbt 2.0

[wing328]

Jul 8th

Ref: https://github.com/OpenAPITools/openapi-generator/milestone/77

[wing328]

@ags313 i just merged it. can you please pull the latest master to test it when you've time?

[bambuchaAdm]

As @ags313 is busy, i can confirm that version for sbt 2.x works well.
There was one adjustment, it was in scope of sbt 2.x migration (task caching), but could be our build customisation.

Thank you @wing328 for fast merge

[Leon0402]

@wing328 Would it be possible, to release a ne version already? Would be nice to have sbt 2 support already and not wait for the next upstream release of openapi generator.