[mike927]

Summary

Prepare the 2.1.0 release. It drops Ruby 3.2 (end of life 2026-03-31): required_ruby_version is now >= 3.3.0. This ships as a minor release because RubyGems and Bundler respect that requirement, so Bundler on Ruby 3.2 keeps resolving 2.0.x instead of failing. Everything else in the release is development tooling.

• VERSION is 2.1.0.
• The CHANGELOG [Unreleased] section is now [2.1.0] - 2026-11-01, and the README and CHANGELOG point Ruby 3.2 users to 2.0.x.
• Gemfile.lock records rspec-json_api (2.1.0), since CI installs with a frozen lockfile.

Tagging v2.1.0 and publishing to RubyGems follow after this merges.

Verification

• rspec (matcher leg) on Ruby 4.0.1 with the frozen lockfile: 112 examples, 0 failures, 98.57% line coverage
• RuboCop: 32 files, no offenses
• A gem build of the first commit (then versioned 3.0.0) declared required_ruby_version >= 3.3.0 with 22 files; the follow-up changes only version strings and docs