INCR-110: Upgrade freezegun

[jcdyer]

Fix broken test by ensuring all datetimes are timezone aware.
@edx/incr-reviewers

[openedx-webhooks]

Thanks for the pull request, @jcdyer! I've created OSPR-3257 to keep track of it in JIRA. JIRA is a place for product owners to prioritize feature reviews by the engineering development teams.

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[jmbowman]

Thanks for the help with the test cleanup!

[openedx-webhooks]

@jcdyer 🎉 Your pull request was merged!

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[natabene]

@jcdyer Thank you for your contribution.