validate false positive when property name is Object method

[fran-worley]

See trailblazer/reform#314 for conversation.

Original description:

Might not be only Object methods, but is definitely at least those:

require "reform/form/active_model/validations"
class BadForm < Reform::Form
  include Reform::Form::ActiveModel::Validations

  property :trust        # or anything from `Object.public_methods`
  validates :trust, presence: true
end

BadForm.new(Struct.new(:trust).new).validate({})
# => true