[Bug] Youtube channel feeds can't be filtered based on article contents

### Describe the bug

When trying to filter Youtube XML feeds, I noticed that search filters weren't applying to content in the video description which is part of the article contents. Not sure if this is an issue with how Youtube delivers the feeds or how the HTML is parsed by FreshRSS. I notice in inspector that the descriptions are ``s and the text is all in italics. Should be easy to reproduce.

### To Reproduce

1. Add a Youtube channel XML feed to FreshRSS (example: https://www.youtube.com/feeds/videos.xml?channel_id=UC1LpsuAUaKoMzzJSEt5WImw )
2. Select the feed and enter a keyword that reflects something present in a video description which shows up as article contents (for example, in the feed above, every description has the word "Patreon")
3. FreshRSS shows no results

### Expected behavior

_No response_

### FreshRSS version

1.23.1

### Environment information

- Intsillation type: Docker

### Additional context

_No response_