Bump GraphQL and GraphQL.SystemTextJson (#1171)

Bumps GraphQL from 8.7.0 to 8.8.0
Bumps GraphQL.SystemTextJson from 8.7.0 to 8.8.0

---
updated-dependencies:
- dependency-name: GraphQL
  dependency-version: 8.8.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: GraphQL.SystemTextJson
  dependency-version: 8.8.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -10,7 +10,7 @@
     <PackageVersion Include="graphiql" Version="2.0.0" />
     <PackageVersion Include="GraphQL" Version="8.8.0" />
     <PackageVersion Include="GraphQL.MicrosoftDI" Version="8.7.0" />
-    <PackageVersion Include="GraphQL.SystemTextJson" Version="8.7.0" />
+    <PackageVersion Include="GraphQL.SystemTextJson" Version="8.8.0" />
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.0.0-beta.7" />
     <PackageVersion Include="Microsoft.AspNetCore.Http" Version="2.3.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.0" />