Bump GraphQL.SystemTextJson from 7.3.0 to 7.3.1 (#531)

Bumps [GraphQL.SystemTextJson](https://github.com/graphql-dotnet/graphql-dotnet) from 7.3.0 to 7.3.1.
- [Release notes](https://github.com/graphql-dotnet/graphql-dotnet/releases)
- [Commits](graphql-dotnet/graphql-dotnet@7.3.0...7.3.1)

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

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

Author: dependabot[bot]

tests/GraphQL.Client.Serializer.Tests/GraphQL.Client.Serializer.Tests.csproj

@@ -8,7 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="GraphQL.NewtonsoftJson" Version="7.3.1" />
-    <PackageReference Include="GraphQL.SystemTextJson" Version="7.3.0" />
+    <PackageReference Include="GraphQL.SystemTextJson" Version="7.3.1" />
   </ItemGroup>
 
   <ItemGroup>