Update actions/cache to v4

[kaessert]

Description of your changes

We started to see

Error: This request has been automatically failed because it uses a deprecated version of `actions/cache: 704facf57e6136b1bc63b828d79edcd491f0ee84`. Please update your workflow to use v3/v4 of actions/cache to avoid interruptions. Learn more: https://github.blog/changelog/2024-12-05-notice-of-upcoming-releases-and-breaking-changes-for-github-actions/#actions-cache-v1-v2-and-actions-toolkit-cache-package-closing-down

for example in https://github.com/upbound/configuration-aws-dynamodb/actions/runs/13630312140/job/38096455549

Issue for reference: https://github.com/upbound/sa-up/issues/262

Fixes #

I have:

• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested