patch 8.2.2136: Vim9: Using uninitialized variable

Problem:    Vim9: Using uninitialized variable.
Solution:   Initialize "len" to zero.  Clean up fnamemodify().
diff --git a/src/version.c b/src/version.c
index 7f78742..0cb1d92 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2136,
+/**/
     2135,
 /**/
     2134,