Fix settings form path

graphql_fragment_include.routing.yml

 graphql_fragment_include.config:
   path: '/admin/config/graphql/fragment-include'
   defaults:
-    _form: '\Drupal\graphql_fragment_include\Form\GraphQLFragmentIncludeConfigForm'
+    _form: '\Drupal\graphql_fragment_include\Form\SettingsForm'
     _title: 'GraphQL Fragment Include Configuration'
   requirements:
     _permission: 'administer site configuration'