Fix `delegate` default serialization with many args

[masoud-msk]

Looks like a typo in default serialization which is (...args) => JSON.stringify(...args) instead of (...args) => JSON.stringify(args) as it doesn't work for example in case of the decorated method having more than 3 arguments or more than 2 arguments with the first one not being an object.

[vlio20]

released in 2.0.9. Thanks @masoud-msk