feat: upgrade to Spring Boot version 3 (#1477)

src/main/resources/webgoat/templates/lesson_content.html

@@ -8,6 +8,6 @@
 <div id="message" class="info" th:utext="${message}"></div>
 <br/>
 
-<div th:replace="lesson:__'lessons/' + ${lesson.package} + '/html/' + ${lesson.id} + '.html'__"></div>
+<div th:replace="~{lesson:__'lessons/' + ${lesson.package} + '/html/' + ${lesson.id} + '.html'__}"></div>
 
 </html>

src/main/resources/webgoat/templates/main_new.html

@@ -229,7 +229,7 @@
 <!-- About WebGoat Modal -->
 <div class="modal" id="about-modal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
     <div class="modal-dialog modal-lg">
-        <div class="modal-content" th:replace="about :: about"></div>
+        <div class="modal-content" th:replace="~{about :: about}"></div>
     </div>
 </div>
 </body>