Allow query option to be a URLSearchParams instance

[sindresorhus]

For better WHATWG URL compatibility.

https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams

URLSearchParams supports a string too, so we could just always run it through URLSearchParams no matter what, for consistency and code simplicity:

got/source/normalize-arguments.js

Lines 72 to 74 in f447378

	if (!is.string(query)) {
	options.query = (new URLSearchParamsGlobal(query)).toString();
	}