Remove freezegun as a test dependency since it is not used

[mikealfare]

Problem

We list freezegun as a test dependency, but it's not used anywhere. It just winds up generating dependabot PRs.

Solution

Remove the dependency. It was left over from the monorepo but does not apply here.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the dbt-redshift contributing guide.

[VersusFacit]

assuming you get tests to pass