patch 8.2.2956: Vim9: need to plan for future additions

Problem:    Vim9: need to plan for future additions.
Solution:   Reserve commands for future use: :type, :class, :enum.
diff --git a/src/version.c b/src/version.c
index 4dc6bd5..b64839e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2956,
+/**/
     2955,
 /**/
     2954,