ci/ghcr: update deprecated docker action versions

[alxndrsn]

Closes #1818

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

• reviewed release notes of all changed actions, noted there were no changes which seemed relevant
• deployed containers using new actions: https://github.com/getodk/central/actions/runs/24562289425
• deployed containers using old actions: https://github.com/getodk/central/actions/runs/24562625907
• confirmed these fail at the final stage for the same reason

Why is this the best possible solution? Were any other approaches considered?

No alternatives considered.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

No effect, unless the published images are bad.

Does this change require updates to documentation? If so, please file an issue here and include the link below.

No.

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