Bump ruby/setup-ruby from 1.283.0 to 1.284.0

Bumps [ruby/setup-ruby](https://github.com/ruby/setup-ruby) from 1.283.0 to 1.284.0.
- [Release notes](https://github.com/ruby/setup-ruby/releases)
- [Changelog](https://github.com/ruby/setup-ruby/blob/master/release.rb)
- [Commits](ruby/setup-ruby@708024e...80740b3)

---
updated-dependencies:
- dependency-name: ruby/setup-ruby
  dependency-version: 1.284.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
-    - uses: ruby/setup-ruby@708024e6c902387ab41de36e1669e43b5ee7085e # v1.283.0
+    - uses: ruby/setup-ruby@80740b3b13bf9857e28854481ca95a84e78a2bdf # v1.284.0
       with:
         bundler-cache: true
     - run: GOVUK_DOCKER_DIR=. make test-ci