Bump SixLabors.ImageSharp in /GraceAttorney.AssetCompiler

Bumps [SixLabors.ImageSharp](https://github.com/SixLabors/ImageSharp) from 1.0.0-rc0003 to 2.1.7.
- [Release notes](https://github.com/SixLabors/ImageSharp/releases)
- [Commits](https://github.com/SixLabors/ImageSharp/commits/v2.1.7)

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

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

GraceAttorney.AssetCompiler/GraceAttorney.AssetCompiler.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="SixLabors.ImageSharp" Version="1.0.0-rc0003" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="2.1.7" />
   </ItemGroup>
 
   <ItemGroup>