patch 8.2.3872: Vim9: finddir() and uniq() return types can be more specific

Problem:    Vim9: finddir() and uniq() return types can be more specific.
Solution:   Adjust the return type.

src/version.c

@@ -749,6 +749,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3872,
 /**/
     3871,
 /**/