patch 9.0.0401: CI uses older clang version

Problem:    CI uses older clang version.
Solution:   Switch from clang 14 to 15. (closes #11066)
diff --git a/src/version.c b/src/version.c
index a46236a..3d6a344 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    401,
+/**/
     400,
 /**/
     399,