Remove version guard from LastException check

In the happy path, the object is a RuntimeError and therefore inherits
from Object. In the sad path, failing when we try to bind the method is
just as informative as failing the actual assertion.

spec/sticky_locals_spec.rb

@@ -29,14 +29,9 @@ describe "Sticky locals (_file_ and friends)" do
         input  '_ex_.message == "halp"'
         output '=> true'
 
-        if Pry::Helpers::BaseHelpers.mri_20? || Pry::Helpers::BaseHelpers.mri_21?
         input  'Kernel.instance_method(:class).bind(_ex_).call'
         output '=> RuntimeError'
       end
-
-        input  '_ex_.wrapped_exception'
-        output /NoMethodError/
-      end
     end
 
     it 'keeps its value after cd-ing' do