[Feature] Ensure PostgreSQL is v15 in all locations

[TimidRobot]

Problem

1. Production Heroku PostgreSQL is v12

   PostgreSQL 12 reaches End of Life on 2024-May-30. Due to security and operational concerns, Heroku cannot run unsupported software as a service.

2. GitHub Actions PostgreSQL is v14
3. Local dev Docker PostgreSQL is v14

Description

Ensure PostgreSQL is v15 in all locations (both local dev and production Heroku)

Additional context

• creativecommons/tech-support#1133 (private repo)
• Heroku Postgres Version Support | Heroku Dev Center
• Upgrading the Version of a Heroku Postgres Database | Heroku Dev Center
• PostgreSQL: Release Notes

Implementation

• [x] I would be interested in implementing this feature.

[TimidRobot]

Production upgraded per Upgrading the Version of a Heroku Postgres Database | Heroku Dev Center:

1. Initialize follower:

   heroku addons:create heroku-postgresql:standard-0 --follow postgresql-sinuous-94712

   • Warning encountered due to heroku/homebrew-brew#37

     Warning: heroku update available from 8.5.0 to 8.10.0.

2. Track status and wait for completion

   heroku pg:wait

3. Enable maintenance mode

   heroku maintenance:on

4. Verify follower is caught up:

   heroku pg:info

5. Upgrade follower database

   heroku pg:upgrade postgresql-flat-93199

6. Track status and wait for completion

   heroku pg:wait

7. Promote new Postgre 15 database

   heroku pg:promote postgresql-flat-93199

8. Verify promotion:

   heroku pg:info

9. Disable maintenance

   heroku maintenance:off

10. Verify app with new database at: https://legaldb.creativecommons.org/

11. Destroy v12 database

    heroku addons:destroy postgresql-sinuous-94712