Omit undefined values from query

[minht11]

I am using qs library and it seems to omit query entirely when its' value is undefined.

import * as qs from 'qs';
import * as pico from 'picoquery';

const data = {
  publicationState: undefined,
};

const query = qs.stringify(data, {
  encodeValuesOnly: true,
});

const newQuery = pico.stringify(data, {
  nestingSyntax: 'index',
});

console.log(query);
console.log(newQuery);

Result: QS: ` Picoquery:publicationState=`

Reproduction

[43081j]

Makes sense to me. Should be an easy fix if you want to contribute

[43081j]

Fixed in #51