appraisal2 3.1.1: Generator-only Appraisal plugins

🏷️ release appraisal2 🏷️ 3.1.1

Version 3.1.1 adds a plugin declaration to the Appraisals DSL. Companion gems can run during Gemfile generation without being copied into the generated dependency scenarios. This keeps generator tooling separate from the dependencies a compatibility test is meant to exercise.

Read the upstream release notes for the complete changes and see the project repository for usage and installation.