Plugin prevents schema export

[nckswt]

Summary

Same as graphile-contrib/postgraphile-plugin-connection-filter#206, attempting to export a schema with this plug errors out with Please ensure this function is wrapped in 'EXPORTABLE(() => ...)'.

Additional context

Noting this discord conversation. I've been trying to find time to PR the solution, but haven't had the chance yet. Making this issue in case anyone else gets to it before I do.

[nckswt]

Resolved by #64