Replace deprecated actions

[jrozner]

Apple-Actions/import-codesign-certs@v2 is using Node 16 which is currently deprecated. According to https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/ all Node 16 actions will be run on Node 20 starting in May. We should determine whether this will break anything and also whether we can replace it with another as it seems to be minimally supported. A number of people have submitted PRs for fixes but they don't seem to be getting merged.