[Feature] Update documentation of integration tests as it relates to CircleCI / GHA

[dbeatty10]

Is this your first time submitting a feature request?

• [X] I have read the expectations for open source contributors
• [X] I have searched the existing issues, and I could not find an existing issue for this feature
• [X] I am requesting a straightforward extension of existing dbt-spark functionality, rather than a Big Idea better suited to a discussion

Describe the feature

Update this documentation to reflect the switch from CircleCI to GitHub Actions in https://github.com/dbt-labs/dbt-spark/pull/923:

https://github.com/dbt-labs/dbt-spark/blob/212442322b509eb34deee2ac000c85c1e4daba73/.github/workflows/release.yml#L89-L94

Describe alternatives you've considered

No response

Who will this benefit?

Up-to-date documentation. I found this instance when doing a code search for "CircleCI".

Are you interested in contributing this feature?

No response

Anything else?

No response