Bump SixLabors.ImageSharp from 3.1.2 to 3.1.3 in /src/BingImageDownload

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](SixLabors/ImageSharp@v3.1.2...v3.1.3)

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

Signed-off-by: dependabot[bot] <support@github.com>

src/BingImageDownload/BingImageDownload.csproj

@@ -38,6 +38,6 @@ See https://github.com/BlythMeister/BingImageDownload for usages</Description>
   <ItemGroup>
     <PackageReference Include="McMaster.Extensions.CommandLineUtils" Version="4.1.1" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.2" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.3" />
   </ItemGroup>
 </Project>