build(deps): bump SixLabors.ImageSharp (#119)

Bumps the nuget group with 1 update in the /src/Eurofurence.App.Server.Services directory: [SixLabors.ImageSharp](https://github.com/SixLabors/ImageSharp).


Updates `SixLabors.ImageSharp` from 3.1.4 to 3.1.5
- [Release notes](https://github.com/SixLabors/ImageSharp/releases)
- [Commits](SixLabors/ImageSharp@v3.1.4...v3.1.5)

---
updated-dependencies:
- dependency-name: SixLabors.ImageSharp
  dependency-type: direct:production
  dependency-group: nuget
...

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