MaxComplexitySchema and MaxDepthSchema leak into subclasses

[xxx]

Heya, thank you for making this gem.

We have some custom error classes defined locally within our gql schema, and these lints are popping for those classes as well.

class MySchema < GraphQL::Schema
  max_complexity 100
  max_depth 10

  class AccountDisabledError < GraphQL::ExecutionError; end # still complains about this, even though they're set in the schema
end

[DmitryTsepelev]

Hey hey! Attached a PR with a fix, will add into the upcoming release 🙂