Update meilisearch-ruby to > v0.28 and deprecated ruby versions prior to 3

[curquiza]

Since version v0.27 of meilisearch-ruby, the ruby 2.x is deprecated, so this PR updates all of the occurrences of the old ruby version.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.29%. Comparing base (e4037a5) to head (2d730ec).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #367 +/- ## ======================================= Coverage 89.29% 89.29% ======================================= Files 13 13 Lines 757 757 ======================================= Hits 676 676 Misses 81 81 ```

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[meili-bors[bot]]

Build succeeded:

• integration-tests (Rails 6.1 with Ruby 3.0)
• integration-tests (Rails 6.1 with Ruby 3.1)
• integration-tests (Rails 6.1 with Ruby 3.2)
• integration-tests (Rails 7 with Ruby 3.0)
• integration-tests (Rails 7 with Ruby 3.1)
• integration-tests (Rails 7 with Ruby 3.2)
• linter-check
• smoke-test