acast: fix test data, support embeds in other pages

[pabs3]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

Fix the acast extractor test data and add support for checking web pages for embeds.

Template

Before submitting a pull request make sure you have:

• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests

In order to be accepted and merged into yt-dlp each piece of code must be in public domain or released under Unlicense. Check all of the following options that apply:

• I am the original author of this code and I am willing to release it under Unlicense
• I am not the original author of this code but it is in public domain or released under Unlicense (provide reliable evidence)

What is the purpose of your pull request?

• Fix or improvement to an extractor (Make sure to add/update tests)
• New extractor (Piracy websites will not be accepted)
• Core bug fix/improvement
• New feature (It is strongly recommended to open an issue first)

Copilot Summary

🤖 Generated by Copilot at cb8a488

Summary

🐛🛠️🌐

Fix and enhance acast extractor. Allow extraction from embedded players by adding _EMBED_REGEX and _WEBPAGE_TESTS to ACastIE in yt_dlp/extractor/acast.py.

Sing, O Muse, of the skillful coder who refined the ACastIE class
And made it fit to parse the webpages where the podcasts are enmassed
He changed the _VALID_URL to match the acast domain and path
And added _EMBED_REGEX and _WEBPAGE_TESTS to aid his craft

Walkthrough

• Rename and update _VALID_URL attribute and add _EMBED_REGEX attribute to ACastIE class (link, link)
• Add _WEBPAGE_TESTS attribute to ACastIE class (link)

[pukkandan]

You can use (?x:pattern) syntax instead of adding an intermediate variable

[pukkandan]

In future, pls avoid force-pushing. Unclean history is fine.

[pabs3]

Personally, I much prefer clean history, but will do. Thanks for merging.

…

-- bye, pabs https://bonedaddy.net/pabs3/