Chores/dep update for v2026.1

[sadiqkhoja]

Closes #1702

Upgraded:

• Node
• Nginx-certbot
• Mail
• Redis
• npm audit fix in test directory
• Postgres

What has been done to verify that this works as intended?

• Updated mail container on test.central.getodk.org and verified that mail is delivered.
• Deployed this PR on dev.getodk.cloud and smoke tested it. Faced Page not found for single submission public link #1716 but doesn't feel like caused by Redis upgrade 🤷‍♂️ Most likely it's a data issue.
• Verified that redirector.conf is not modified in the docker-nginx-certbot
• Tests are passing https://github.com/sadiqkhoja/central/actions/runs/23562708269

Before submitting this PR, please make sure you have:

• branched off and targeted the next branch OR only changed documentation/infrastructure (master is stable and used in production)
• verified that any code or assets from external sources are properly credited in comments or that everything is internally sourced

[lognaturel]

Thank you! I don't think we should update the submodules here. Otherwise everything else looks good.