patch 8.2.1447: Vim9: return type of keys() is list<any>

Problem:    Vim9: return type of keys() is list<any>.
Solution:   Should be list<string>. (closes #6711)
diff --git a/src/version.c b/src/version.c
index a8a1d49..11dd396 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1447,
+/**/
     1446,
 /**/
     1445,