Bump SixLabors.ImageSharp from 1.0.0 to 2.1.8 in /sources/Voltium.Common

Bumps [SixLabors.ImageSharp](https://github.com/SixLabors/ImageSharp) from 1.0.0 to 2.1.8.
- [Release notes](https://github.com/SixLabors/ImageSharp/releases)
- [Commits](SixLabors/ImageSharp@v1.0.0...v2.1.8)

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

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

sources/Voltium.Common/Voltium.Common.csproj

@@ -17,7 +17,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging" Version="5.0.0-preview.4.20251.6" />
     <PackageReference Include="Microsoft.Toolkit.HighPerformance" Version="7.1.2" />
     <PackageReference Include="NonCopyableAnalyzer" Version="0.6.0" />
-    <PackageReference Include="SixLabors.ImageSharp" Version="1.0.0" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="2.1.8" />
     <PackageReference Include="TerraFX.Interop.Mimalloc" Version="1.6.0-beta2" />
     <PackageReference Include="TerraFX.Interop.Windows" Version="10.0.22000-rc1" />
     <PackageReference Include="TerraFX.Interop.Libc" Version="1.2017.0-beta3" />