message: Correctly use cookies when fetching schema
  This implementation currently fails to send cookies along with a request (even though that was intended).
  This is because `credentials: include` is included in the list of headers rather than being passed as an option.
  Fixes
diff: @@ -28,10 +28,10 @@ export class SchemaFetcher {
  ): Promise<{ schema: GraphQLSchema; tracingSupported: boolean } | null> {
  const response = await fetch(endpoint, {
  method: 'post',
  + credentials: 'include',
  headers: {
  'Content-Type': 'application/json',
  'X-Apollo-Tracing': '1',
  - credentials: 'include',
  ...headers,
  },
  body: JSON.stringify({ query: introspectionQuery }),
  