Bump ffmpeg-for-homebridge from 2.1.1 to 2.1.5

Bumps [ffmpeg-for-homebridge](https://github.com/homebridge/ffmpeg-for-homebridge) from 2.1.1 to 2.1.5.
- [Release notes](https://github.com/homebridge/ffmpeg-for-homebridge/releases)
- [Commits](homebridge/ffmpeg-for-homebridge@v2.1.1...v2.1.5)

---
updated-dependencies:
- dependency-name: ffmpeg-for-homebridge
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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