Remove problematic did_you_mean spec

I had thought did_you_mean for KeyErrors was available in Ruby 2.3 and
higher, but this spec seems to be failing for Ruby 2.3 and 2.4.
Since we have OK coverage of the custom KeyError message behavior
elsewhere, I don't think this test is essential.

spec/factory_bot/registry_spec.rb

@@ -21,12 +21,6 @@ describe FactoryBot::Registry do
       to raise_error(KeyError, "Great thing not registered: \"object_name\"")
   end
 
-  it "includes a did_you_mean message" do
-    subject.register(:factory_bot, registered_object)
-    expect { subject.find(:factory_bit) }.
-      to raise_error(KeyError, /Did you mean\?  "factory_bot"/)
-  end
-
   it "adds and returns the object registered" do
     expect(subject.register(:object_name, registered_object)).to eq registered_object
   end