Bump SixLabors.ImageSharp from 3.1.4 to 3.1.5 in /GlennLibTests (#34)

Bumps [SixLabors.ImageSharp](https://github.com/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
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

GlennLib/GlennLib.csproj

@@ -9,7 +9,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <PackageReference Include="SixLabors.ImageSharp" Version="3.1.4" />
+      <PackageReference Include="SixLabors.ImageSharp" Version="3.1.5" />
     </ItemGroup>
 
     <ItemGroup>

GlennLibTests/GlennLibTests.csproj

@@ -11,7 +11,7 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
-        <PackageReference Include="SixLabors.ImageSharp" Version="3.1.4" />
+        <PackageReference Include="SixLabors.ImageSharp" Version="3.1.5" />
         <PackageReference Include="xunit" Version="2.7.0" />
         <PackageReference Include="xunit.runner.visualstudio" Version="2.5.7">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>