Fix: initialise active support in logger

What does this MR do and why?

• Resolves #33 (closed)

• Updates the specs to use activesupport 7.0.8 to be similar to jobs using this gem (e.g. https://gitlab.com/gitlab-org/gitlab/-/jobs/5451090816#L654)

In #33 (closed) the job is failing due to an uninitialised constant while using active support 7.0.8. We need to require active_support before requiring the extension: https://guides.rubyonrails.org/active_support_core_extensions.html#cherry-picking-a-definition

How to set up and validate locally

• Reproduce using steps: #33 (closed)

Then apply the fix and re-run the specs with: bundle exec rspec

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.