Bump SixLabors.ImageSharp from 3.1.7 to 3.1.12 (#63)

---
updated-dependencies:
- dependency-name: SixLabors.ImageSharp
  dependency-version: 3.1.12
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: SixLabors.ImageSharp
  dependency-version: 3.1.12
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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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="3.1.7" />
+      <PackageReference Include="SixLabors.ImageSharp" Version="3.1.12" />
     </ItemGroup>
 
     <ItemGroup>

GlennLibTests/GlennLibTests.csproj

@@ -11,7 +11,7 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.7.0" />
-        <PackageReference Include="SixLabors.ImageSharp" Version="3.1.7" />
+        <PackageReference Include="SixLabors.ImageSharp" Version="3.1.12" />
         <PackageReference Include="xunit" Version="2.7.0" />
         <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>