build(deps): update av requirement from <14 to <15

Updates the requirements on [av](https://github.com/PyAV-Org/PyAV) to permit the latest version.
- [Changelog](https://github.com/PyAV-Org/PyAV/blob/main/CHANGELOG.rst)
- [Commits](PyAV-Org/PyAV@v0.1.0...v14.1.0)

---
updated-dependencies:
- dependency-name: av
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

pyproject.toml

@@ -81,9 +81,9 @@ hf = [
   "datasets[audio,vision]>=2.21.0"
 ]
 video = [
-  # Use 'av<14' because of incompatibility with imageio
+  # Use 'av<15' because of incompatibility with imageio
   # See https://github.com/PyAV-Org/PyAV/discussions/1700
-  "av<14",
+  "av<15",
   "ffmpeg-python",
   "imageio[ffmpeg]",
   "opencv-python"