Bump System.Text.Json from 8.0.0 to 8.0.4

Bumps System.Text.Json from 8.0.0 to 8.0.4.

---
updated-dependencies:
- dependency-name: System.Text.Json
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

test/FluentRest.Tests/FluentRest.Tests.csproj

@@ -15,6 +15,7 @@
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Http" Version="8.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
+    <PackageReference Include="System.Text.Json" Version="8.0.4" />
     <PackageReference Include="Testcontainers" Version="3.9.0" />
     <PackageReference Include="XUnit.Hosting" Version="1.7.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">