Bump SixLabors.ImageSharp in /src/ApplicationCore

Bumps [SixLabors.ImageSharp](https://github.com/SixLabors/ImageSharp) from 1.0.0-rc0002 to 2.1.8.
- [Release notes](https://github.com/SixLabors/ImageSharp/releases)
- [Commits](https://github.com/SixLabors/ImageSharp/commits/v2.1.8)

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

Signed-off-by: dependabot[bot] <[email protected]>

src/ApplicationCore/ApplicationCore.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="SixLabors.ImageSharp" Version="1.0.0-rc0002" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="2.1.8" />
   </ItemGroup>
 
 </Project>