'https://cors-anywhere.herokuapp.com/' is also broken

See https://github.com/Rob--W/cors-anywhere/issues/301

Signed-off-by: Peter Chubb <peter.chubb@unsw.edu.au>

Author: wom-bat

htmlpreview.js

@@ -89,7 +89,6 @@
 
 	var fetchProxy = function (url, options, i) {
 		var proxy = [
-			'https://cors-anywhere.herokuapp.com/',
 			'https://api.codetabs.com/v1/proxy/?quest='
 		];
 		return fetch(proxy[i] + url, options).then(function (res) {