[ie] Do not test truth value of xml.etree.ElementTree.Element

[bashonly]

Testing the truthiness of an xml.etree.ElementTree.Element instance is deprecated in py3.12

Refs:

• https://docs.python.org/3/library/xml.etree.elementtree.html#element-objects
• https://docs.python.org/3/whatsnew/3.12.html#pending-removal-in-python-3-14

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 b8d5508

Summary

🐛🧹🌐

Added XML parsing and error handling for various extractors that deal with XML-based formats or endpoints. Modified common.py to check for valid MPD responses before using them. Sorted imports in cbc.py for readability.

We parse the XML, we handle the errors
We extract the formats from the web of terrors
We defy the failures, we resist the invalid
We are the InfoExtractors, we are the metal avid

Walkthrough

• Add xml.etree.ElementTree module to parse XML responses from some CBC, MTV, NBC and SlidesLive endpoints (link, link, link, link)

• _find_secret_formats in CBCGemIE (link)
• _extract_mpd_vod_duration in InfoExtractor (link)
• _get_video_info in MTVServicesInfoExtractor (link)
• _real_extract in NBCStationsIE (link)
• _real_extract in SlidesLiveIE (link)