build(deps)!: update actions to Node.js 24 runtime

[shaanmajid]

Summary

• Update actions/cache from v4 to v5 and actions/github-script from v7 to v8 to use the Node.js 24 runtime
• Resolves Node.js 20 deprecation warnings that GitHub-hosted runners now emit for actions using node20

Breaking change

Self-hosted runners must have Node.js 24 available. GitHub-hosted runners already include Node.js 24, but self-hosted runners on older images may not. GitHub plans to remove the node20 runtime from hosted runners in September 2026. See here for more info.

Fixes #200

[shaanmajid]

Example warning when using this action (from https://github.com/zizmorcore/zizmor/actions/runs/24038268849):

[adriencaccia]

Thanks for the contribution @shaanmajid!

Regarding the breaking change, we can safely release this as a patch instead:

Node.js 24 support was added in actions/runner v2.327.0 almost a year ago. It means that all actions with using: node24 will use the Node.js 24 shipped as an external by the actions/runner app. Per GitHub's self-hosted runner update policy:

If you disable automatic updates, you will be required to update your runner
version within 30 days of a new version being made available.

Thus all runners, self-hosted or not, must already have a version that works.

And in addition, this PR fixes #200