Update Marshal.dump specs to check error message for anonymous classes and modules.

Co-authored-by: Stan Lo <stan.lo@shopify.com>

Author: nirvdrum

spec/ruby/core/marshal/dump_spec.rb

@@ -222,7 +222,7 @@ def _dump(level)
     end
 
     it "raises TypeError with an anonymous Module" do
-      -> { Marshal.dump(Module.new) }.should raise_error(TypeError)
+      -> { Marshal.dump(Module.new) }.should raise_error(TypeError, /can't dump anonymous module/)
     end
   end