Updated query param constructor to inherit from Property (no clue why it was not done) and split the constructor to use `update` function. Also, made the toString() function of query param use `unparseSingle`
Updated query param constructor to inherit from Property (no clue why it was not done) and split the constructor to use `update` function. Also, made the toString() function of query param use `unparseSingle`

postmanlabs/postman-collection