Bump SixLabors.ImageSharp from 3.1.12 to 4.0.0

---
updated-dependencies:
- dependency-name: SixLabors.ImageSharp
  dependency-version: 4.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

src/ks0223-web-mac/backend/backend.csproj

@@ -20,7 +20,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.ML.OnnxRuntime" Version="1.18.1" />
-    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.12" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="4.0.0" />
   </ItemGroup>
 
   <ItemGroup>