Bump ffmpeg-windows-build-helpers from 7cc7cb4 to 9be2c8b

Bumps [ffmpeg-windows-build-helpers](https://github.com/rdp/ffmpeg-windows-build-helpers) from `7cc7cb4` to `9be2c8b`.
- [Release notes](https://github.com/rdp/ffmpeg-windows-build-helpers/releases)
- [Commits](rdp/ffmpeg-windows-build-helpers@7cc7cb4...9be2c8b)

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

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

Author: dependabot[bot]