Fix deprecation warning on treat_symbols_as_metadata_keys_with_true_values
Fix deprecation warning on treat_symbols_as_metadata_keys_with_true_values

It is now set to true as default and setting it to false has no effect.

taiki45/chanko,damoguyan8844/chanko,damoguyan8844/chanko,cookpad/chanko,cookpad/chanko,taiki45/chanko,damoguyan8844/chanko,cookpad/chanko,taiki45/chanko