fixes JoyChou93#23

Author: JoyChou93

src/main/resources/templates/login.html

@@ -8,7 +8,7 @@
     <meta name="_csrf_headerName" th:content="${_csrf.headerName}" />
     <meta name="_csrf_parameterName" th:content="${_csrf.parameterName}" />
     <link rel="stylesheet" th:href="@{/css/login.css}" type="text/css" />
-    <script th:src="@{https://code.jquery.com/jquery-3.4.1.min.js}"></script>
+    <script th:src="@{https://cdn.jsdelivr.net/npm/jquery@3.4.1/dist/jquery.min.js}"></script>
 
     <script>
         window.csrfToken = {