Fix check of RSpec.configure presence.

[viktorchukhantsev]

What is the purpose of this pull request?

Fix issue when RSpec.configure isn't defined yet, but the RSpec module already exists.

What changes did you make? (overview)

Just add an additional check that RSpec.configuration is defined.

Is there anything you'd like reviewers to focus on?

Checklist

• [ ] I've added tests for this change
• [ ] I've added a Changelog entry
• [ ] I've updated a documentation

[viktorchukhantsev]

@palkan I added all fixes. One check failed somewhere in Github Actions. Can you relaunch it?

[palkan]

Thanks!