Revert "Merge pull request #1650 from sampersand/swesterman/23-11-26/…

…bugfix-RBS.Test.Errors.inspect_"

This reverts commit b9930cb, reversing
changes made to a15863f.

lib/rbs/test/errors.rb

@@ -29,11 +29,8 @@ def self.format_param(param)
         end
       end
 
-      RESPOND_TO = ::Kernel.instance_method :respond_to?
-      private_constant :RESPOND_TO
-
       def self.inspect_(obj)
-        if RESPOND_TO.bind_call(obj, :inspect)
+        if obj.respond_to?(:inspect)
           obj.inspect
         else
           Test::INSPECT.bind(obj).call     # For the case inspect is not defined (like BasicObject)