Bump GraphQL.SystemTextJson from 8.6.0 to 8.7.0

---
updated-dependencies:
- dependency-name: GraphQL.SystemTextJson
  dependency-version: 8.7.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

GraphQLNetExample/GraphQLNetExample.csproj

@@ -11,7 +11,7 @@
     <PackageReference Include="GraphQL.MicrosoftDI" Version="8.7.0" />
     <PackageReference Include="GraphQL.Server.Transports.AspNetCore" Version="8.3.2" />
     <PackageReference Include="GraphQL.Server.Ui.Altair" Version="8.3.2" />
-    <PackageReference Include="GraphQL.SystemTextJson" Version="8.6.0" />
+    <PackageReference Include="GraphQL.SystemTextJson" Version="8.7.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="9.0.10">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>