patch 8.2.3401: Vim9: cannot use negative count with finddir() and findfile()

Problem:    Vim9: cannot use a negative count with finddir() and findfile().
Solution:   Adjust the return type. (closes #8776)
diff --git a/src/version.c b/src/version.c
index 7482d3f..8f502cc 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3401,
+/**/
     3400,
 /**/
     3399,