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)

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3401,
 /**/
     3400,
 /**/