Update default ruby version in examples
What does this MR do?
Updates the example ruby version from 2.7 to 3.3 in documentation examples.
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Why was this MR needed?
Updates the default ruby version use the 3.3 version. Ruby version 2.7 was released in 2019 and lost support over 2 years ago. To keep the documentation and prompts fresh we should update the string to avoid using "stale" data.
What's the best way to test this MR?
By checking the documentation and/or tests. You can also run gitlab-runner register and observe the string version being returned (expected ruby:3.3):