build(deps): bump youtube-transcript-api from 0.6.3 to 1.0.3 in /backend

Bumps [youtube-transcript-api](https://github.com/jdepoix/youtube-transcript-api) from 0.6.3 to 1.0.3.
- [Release notes](https://github.com/jdepoix/youtube-transcript-api/releases)
- [Commits](https://github.com/jdepoix/youtube-transcript-api/compare/v0.6.3...v1.0.3)

---
updated-dependencies:
- dependency-name: youtube-transcript-api
  dependency-version: 1.0.3
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements.txt

@@ -93,7 +93,7 @@ authlib==1.4.1
 
 black==25.1.0
 langfuse==2.44.0
-youtube-transcript-api==0.6.3
+youtube-transcript-api==1.0.3
 pytube==15.0.0
 
 extract_msg