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>

ErsatzTV.Infrastructure/ErsatzTV.Infrastructure.csproj

@@ -35,7 +35,7 @@
         <PackageReference Include="Refit.Xml" Version="11.2.0" />
         <PackageReference Include="RichTextKit.Stbear" Version="0.4.167.3" />
         <PackageReference Include="Scriban.Signed" Version="7.2.4" />
-        <PackageReference Include="SixLabors.ImageSharp" Version="3.1.12" />
+        <PackageReference Include="SixLabors.ImageSharp" Version="4.0.0" />
         <PackageReference Include="SkiaSharp" Version="3.119.4" />
         <PackageReference Include="TagLibSharp" Version="2.3.0" />
         <PackageReference Include="TimeZoneConverter" Version="7.2.0" />