Address breakages forthcoming in ubuntu-latest's switch from 22.04 to 24.04

[tsibley]

GitHub announced changes to ubuntu-latest¹ (h/t @genehack):

We will migrate the ubuntu-latest label to ubuntu 24 starting on December 5, 2024 and ending on January 17, 2025. The ubuntu 24 image has a different set of tools and packages than ubuntu 22. We have made cuts to the list of packages so that we can maintain our SLA for free disk space. This may break your workflows if you depend on certain packages that have been removed. Please review this list to see if you are using any affected packages.

I reviewed the list and noted removed software that may break us based on things I know we use or may use:

• Heroku CLI
• Terraform
• Netlify CLI
• Vercel CLI

A bunch of pre-fetched Docker images we use are also removed, so that may lead to slightly increased CI run times.

We use ubuntu-latest in a bunch of places; all those stand to potentially break as early as 5 Dec. As the migration is happening over the winter holidays and new year, we'd be best to take care of it all before 5 Dec instead of taking the chance of breaking while many folks are out.

We can test what will break by updating places that use ubuntu-latest (currently an alias for ubuntu-22.04) to use ubuntu-24.04 instead. Once any issues are resolved, I'd then recommend leaving the specific version in place. This will ensure stability until we're required to update it again in the future.

¹ The other changes to GitHub Actions also announced will not impact us, AFAICT.

[joverlee521]

Seasonal flu is the only repo using Netlify CLI and the workflow installs an older version via npm so it should not be affected by the removal.