Bump SixLabors.ImageSharp from 3.1.2 to 3.1.3 in /GlennLibTests (#24)

Bumps [SixLabors.ImageSharp](https://github.com/SixLabors/ImageSharp) from 3.1.2 to 3.1.3.
- [Release notes](https://github.com/SixLabors/ImageSharp/releases)
- [Commits](https://github.com/SixLabors/ImageSharp/compare/v3.1.2...v3.1.3)

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

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GlennLibTests/GlennLibTests.csproj

@@ -11,7 +11,7 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
-        <PackageReference Include="SixLabors.ImageSharp" Version="3.1.2" />
+        <PackageReference Include="SixLabors.ImageSharp" Version="3.1.3" />
         <PackageReference Include="xunit" Version="2.7.0" />
         <PackageReference Include="xunit.runner.visualstudio" Version="2.5.7">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>