HTTPClient library supports https using a fingerprint (SHA1) which can be extracted from the browser. This hash is outdated and should be replaced at some point. For now it is the easiest way to do a HTTPS request. Another option might be using a [using CA certificate via the WiFiClientSecure library](https://github.com/esp8266/Arduino/blob/master/libraries/ESP8266WiFi/examples/HTTPSRequestCACert/HTTPSRequestCACert.ino).