Bump SkiaSharp from 2.88.3 to 2.88.6 in /src/PdfLibCore.SkiaSharp (#20)

Bumps [SkiaSharp](https://github.com/mono/SkiaSharp) from 2.88.3 to 2.88.6.
- [Release notes](https://github.com/mono/SkiaSharp/releases)
- [Commits](mono/SkiaSharp@v2.88.3...v2.88.6)

---
updated-dependencies:
- dependency-name: SkiaSharp
  dependency-type: direct:production
...

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src/PdfLibCore.SkiaSharp/PdfLibCore.SkiaSharp.csproj

@@ -35,7 +35,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <PackageReference Include="SkiaSharp" Version="2.88.3" />
+      <PackageReference Include="SkiaSharp" Version="2.88.6" />
       <PackageReference Include="SkiaSharp.NativeAssets.Linux" Version="2.88.3" />
     </ItemGroup>