Change sample picture due to certificate issues

Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/resources/templates/booklist.html

@@ -250,7 +250,7 @@ Idea of the following syntax used in this and other HTML document:
 			<p th:text="${#messages.msgOrNull('page.text.list.anon.info')} ?: 'page.text.list.anon.info'">
 			page.text.list.anon.info
 			</p>
-			<img src="http://dreamicus.com/data/abyss/abyss-08.jpg" style="max-width: 600px; height: auto;" alt="abyss">
+			<img src="https://w.wallhaven.cc/full/96/wallhaven-96y9qk.jpg" style="max-width: 900px; height: auto;" alt="abyss">
 		</div>
 	</div>
 	<th:block th:insert="fragments/footerpart :: footerpart"/>