Fix lang toggle

This is not perfect as the toggle is not set to the right position when
the site is reload but as @Wal_ said he would refactor, I just made a
working sample good enough imo

frontend/src/utils.js

@@ -19,7 +19,7 @@ export function getCookie(key){
  * @param key cookie name
  */
 export function setCookie(key, value){
-	cookie = key + "=" + value + ";";
+	let cookie = key + "=" + value + "; SameSite=Lax";
 	document.cookie = cookie;
 	// Here we can apreciate the stupidity of Javascript :/
 }