chore(deps): bump System.Text.Json in /src/shell/dotnet/Shell

Bumps [System.Text.Json](https://github.com/dotnet/runtime) from 6.0.8 to 7.0.4.
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](dotnet/runtime@v6.0.8...v7.0.4)

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

Signed-off-by: dependabot[bot] <[email protected]>

Directory.Packages.props

@@ -49,7 +49,7 @@
     <PackageVersion Include="System.Reactive.Async" Version="6.0.0-alpha.18" />
     <PackageVersion Include="System.Reactive" Version="6.0.0" />
     <PackageVersion Include="System.ServiceModel.Primitives" Version="6.0.0" />
-    <PackageVersion Include="System.Text.Json" Version="6.0.9" />
+    <PackageVersion Include="System.Text.Json" Version="7.0.4" />
     <PackageVersion Include="TestableIO.System.IO.Abstractions.Wrappers" Version="19.2.69" />
     <PackageVersion Include="TestableIO.System.IO.Abstractions" Version="20.0.15" />
     <PackageVersion Include="Testably.Abstractions.Testing" Version="2.4.1" />