Prepare for scpca-docs release: New age columns

Steps for a new release of `scpca-docs`

This should include updates for the age columns - age and age_timing.

[x] Does this release require an update to the CHANGELOG because there will be changes to downloadable files? If so, please create an issue tracking the CHANGELOG update and mark it as blocking this issue.
[x] Are all other issues planned for this release resolved? If any issues are unresolved, mark this issue as blocked by those on ZenHub.
[x] Optional: If not all changes in development are ready to be released, create a feature branch off main and cherry pick commits from development to that feature branch.
[x] File a PR from the development branch (or the new feature branch) to the main branch. This should include all of the changes that will be associated with the next release.
- [x] If a CHANGELOG entry was required, add the date to the entry's header as part of this PR.

[x] On the releases page, choose Draft a new release.
[x] In Choose a tag, use the current date as the release tag (YYYY.MM.DD), then click Create a new tag: YYYY.MM.DD on publish.
[x] Write a description of the major changes in this release. You may want to start with the auto-generated release notes to save time.
[ ] Optional: If not all issues have been addressed, save a draft to return to later.
[x] Publish the release!