Bump SixLabors.ImageSharp from 1.0.3 to 1.0.4 (#144)

Bumps [SixLabors.ImageSharp](https://github.com/SixLabors/ImageSharp) from 1.0.3 to 1.0.4.
- [Release notes](https://github.com/SixLabors/ImageSharp/releases)
- [Commits](https://github.com/SixLabors/ImageSharp/compare/v1.0.3...v1.0.4

)

---
updated-dependencies:
- dependency-name: SixLabors.ImageSharp
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

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