Fix raise_error deprecation warning

Author: Marc Huffnagle

spec/unit/puppet/functions/mysql_deepmerge_spec.rb

@@ -30,7 +30,7 @@
     end
 
     it 'should accept empty strings as puppet undef' do
-      expect { new_hash = scope.function_mysql_deepmerge([{}, ''])}.not_to raise_error(Puppet::ParseError, /unexpected argument type String/)
+      expect { new_hash = scope.function_mysql_deepmerge([{}, ''])}.not_to raise_error
     end
 
     it 'should be able to mysql_deepmerge two hashes' do