⬆️ Bump streamlink from 2.4.0 to 3.0.3 in /tvheadend (#59)

Bumps [streamlink](https://github.com/streamlink/streamlink) from 2.4.0 to 3.0.3.
- [Release notes](https://github.com/streamlink/streamlink/releases)
- [Changelog](https://github.com/streamlink/streamlink/blob/master/CHANGELOG.md)
- [Commits](https://github.com/streamlink/streamlink/compare/2.4.0...3.0.3)

---
updated-dependencies:
- dependency-name: streamlink
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

tvheadend/requirements.txt

@@ -1,2 +1,2 @@
 setuptools==58.4.0
-streamlink==2.4.0
+streamlink==3.0.3