Maintenance updates

[jonavellecuerdo]

Purpose and background context

Implement minor maintenance updates as part of Heroku software updates (Heroku stack and Redis).
This PR serves as a way to maintain the standard deployment workflow for Heroku apps (i.e.,
PR creates review app, merging PR deploys to staging, and a promote to production via Heroku Dashboard).

Regarding the second commit for disabling SSL certificates:
This change was required by the upgrade of Redis from version 6.2.14 to 7.2.

1. What does this do?
   This instructs Celery to not verify the Redis broker URL.
2. What are the changes?
   Update the base Django settings file to append "?ssl_cert_reqs=none" at the end of the CELERY_BROKER_URL config variable and update the default broker url to use "rediss" syntax to accept appended syntax.

How can a reviewer manually see the effects of these changes?

1. Confirm linters pass (Note: ruff is not included at this time).
2. Confirm all unit tests are passing.
3. Review sample email sent to Solenoid Admins. Look for subject heading: "OA outreach message to forward: "

Includes new or updated dependencies?

YES - Updated to use Python 3.12.

Changes expectations for external applications?

NO

What are the relevant tickets?

• https://mitlibraries.atlassian.net/browse/IN-1075

Developer

• All new ENV is documented in README
• All new ENV has been added to staging and production environments
• All related Jira tickets are linked in commit message(s)
• Stakeholder approval has been confirmed (or is not needed)

Code Reviewer(s)

• The commit message is clear and follows our guidelines (not just this PR message)
• There are appropriate tests covering any new functionality
• The provided documentation is sufficient for understanding any new functionality introduced
• Any manual tests have been performed or provided examples verified
• New dependencies are appropriate or there were no changes

[jonavellecuerdo]

Note: We are waiting to hear back from @JPrevost to confirm that disabling SSL checks is okay for this application. 🤔

[ehanson8]

No concerns on my end but just commenting until Jeremy's approval is confirmed so the PR isn't accidentally merged

[ghukill]

Approved! The discussion continues outside of this PR about some intricacies of how and when the SSL errors are bubbling up, but given it's working in staging with these changes, pushing to production to test there would be beneficial.