Bump System.Text.Json in /src/GraphQL.Client.Serializer.SystemTextJson

Bumps System.Text.Json from 8.0.3 to 8.0.4.

---
updated-dependencies:
- dependency-name: System.Text.Json
  dependency-type: direct:production
...

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

Author: dependabot[bot]

src/GraphQL.Client.Serializer.SystemTextJson/GraphQL.Client.Serializer.SystemTextJson.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0'">
-    <PackageReference Include="System.Text.Json" Version="8.0.3" />
+    <PackageReference Include="System.Text.Json" Version="8.0.4" />
   </ItemGroup>
 
   <ItemGroup>