chore: bump Microsoft.AspNetCore.Mvc.NewtonsoftJson in /src (#260)

Bumps [Microsoft.AspNetCore.Mvc.NewtonsoftJson](https://github.com/dotnet/aspnetcore) from 7.0.11 to 7.0.12.
- [Release notes](https://github.com/dotnet/aspnetcore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/main/docs/ReleasePlanning.md)
- [Commits](dotnet/aspnetcore@v7.0.11...v7.0.12)

---
updated-dependencies:
- dependency-name: Microsoft.AspNetCore.Mvc.NewtonsoftJson
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/UnityNuGet.Server/UnityNuGet.Server.csproj

@@ -17,7 +17,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.21.0" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="7.0.11" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="7.0.12" />
     <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="7.0.0" />
     <PackageReference Include="Microsoft.Extensions.Options.DataAnnotations" Version="7.0.0" />
     <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.19.5" />