feat: add alpine:3.24 dind

[janishorsts]

Adds support for a new Alpine-3.24 Docker-in-Docker (dind) image.

[github-actions]

🎉 Are we earthbuild yet?

Great progress! You've reduced "earthly" occurrences by 1 (4.35%)

📈 Overall Progress

Branch	Total Count
main	23
This PR	22
Difference	-1 (4.35%)

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Keep up the great work migrating from Earthly to Earthbuild! 🚀

💡 Tips for finding more occurrences

Run locally to see detailed breakdown:

./.github/scripts/count-earthly.sh

Note that the goal is not to reach 0.
There is anticipated to be at least some occurences of earthly in the source code due to backwards compatibility with config files and language constructs.

[gemini-code-assist]

Code Review

This pull request adds support for Alpine 3.24 by introducing a new Earthfile under os/alpine-3.24/, updating Renovate configurations, and documenting the new version in README.md and CONTRIBUTING.md. The review feedback highlights a few typographical errors in the comments of the newly added Earthfile that should be corrected.

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