Update versions and remove unused dependency

[mathemancer]

Fixes #3514

• Updates Python to 3.13 for all docker files.
• Updates PostgreSQL to 17 for Mathesar docker image.
• Updates Documentation to make our version support strategy more transparent.
• Updates Documentation to remove unused gettext dependency.

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the develop branch of the repository
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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[seancolsen]

Very nice. That new version support page is really helpful!

[Anish9901]

LGTM!