Minimum required PHP version is now 7.1.3.
The library now has PHP7.1 type-hints and declare(strict_types=1) everywhere. Please make sure the values
passed to the library match the type.
Since Yahoo Finance YQL API stopped working in November 2017, this client switched to a different endpoint.
Because of that the Quote entity changed according to the fields available from the new API endpoint.
Also, exchange rates are now represented as Quote entities.