Bump ffmpeg-windows-build-helpers from f8f1bbf to 9731884

Bumps [ffmpeg-windows-build-helpers](https://github.com/rdp/ffmpeg-windows-build-helpers) from `f8f1bbf` to `9731884`.
- [Release notes](https://github.com/rdp/ffmpeg-windows-build-helpers/releases)
- [Commits](rdp/ffmpeg-windows-build-helpers@f8f1bbf...9731884)

---
updated-dependencies:
- dependency-name: ffmpeg-windows-build-helpers
  dependency-type: direct:production
...

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

Author: dependabot[bot]