chore: assert the presence of the yt-dlp dep

[miraclx]

Add a test to ensure the yt-dlp binary is present after install has been run.

Found out why CI was failing, over-dependence on caches. Looks like 2 months ago, we cached an image that didn't appropriately download the yt-dlp subdependency of youtube-dl-exec and we kept reusing that image since freyr didn't change in this period of time.

Had to evict caches, and now it works! - miraclx/freyr-js/actions/runs/8623905754/job/23690297872

Originally posted by @miraclx in #669 (comment)

Linked: microlinkhq/youtube-dl-exec#190

[github-actions]

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🐋 🤖

A docker image for this PR has been built!

docker pull freyrcli/freyrjs-git:pr-670

Base (master)
This Patch

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What's this?

This docker image is a self-contained sandbox that includes all the patches made in this PR. Allowing others to easily use your patches without waiting for it to get merged and released officially.

For more context, see https://github.com/miraclx/freyr-js#docker-development.