chore: update Ruby version from 3.1 to 3.4 in workflows and README

[kinyoklion]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

• Failing CI job — Bundler found conflicting requirements for the Ruby version when running with Ruby 3.1.7.

Describe the solution you've provided

The openfeature-sdk ~> 0.6.0 dependency requires Ruby >= 3.4, and the gemspec's required_ruby_version was already updated to >= 3.4 in #16. However, three workflows and the README still referenced Ruby 3.1:

1. release-please.yml — used ruby-version: 3.1 for the CI step during release → updated to 3.4
2. manual-publish.yml — used ruby-version: 3.1 for the build-and-test step → updated to 3.4
3. manual-publish-docs.yml — used ruby-version: 3.1 for setup-ruby → updated to 3.4
4. README.md — stated "Ruby 3.1 and above" → updated to "Ruby 3.4 and above"

Describe alternatives you've considered

• Widening openfeature-sdk to ~> 0.4 to restore Ruby 3.1 support: Rejected per reviewer feedback — the intent is to keep openfeature-sdk ~> 0.6.0 and require Ruby 3.4+.

Additional context

The ci.yml workflow was already updated to Ruby 3.4 in #16; only the release/publish workflows were missed.

Human review checklist

• Verify no other files still reference Ruby 3.1 (e.g. grep for 3.1 across .github/)

Link to Devin session: https://app.devin.ai/sessions/0a8e066ab2c447618bcefa0be007594a
Requested by: @kinyoklion

---

Note

Low Risk
Low risk: updates only CI/release GitHub Actions configuration and README text, with no runtime code changes. Main risk is CI/publish failures if Ruby 3.4 environment assumptions differ from prior runs.

Overview
Aligns automation and documentation with the project’s Ruby 3.4+ requirement by updating GitHub Actions workflows to run build/test, release, and docs publishing using Ruby 3.4 instead of 3.1.

Updates the README to state support for Ruby 3.4 and above.

^{Written by Cursor Bugbot for commit 53daf5e. This will update automatically on new commits. Configure here.}

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring

[devin-ai-integration]

@cursor review

[kinyoklion]

We want to keep the version support as it was, but increase the version of ruby we are using.

[devin-ai-integration]

Got it — reverted the dependency and gemspec changes. The PR now just updates the README to say Ruby 3.4+ to match the actual required_ruby_version in the gemspec.

[kinyoklion]

The CI failure is because CI didn't use 3.4. So there must be workflow updates needed.

[devin-ai-integration]

Found it — release-please.yml, manual-publish.yml, and manual-publish-docs.yml all still had ruby-version: 3.1. Updated all three to 3.4.