patch 8.2.1657: Vim9: no proper error for nested ":def!"

Problem:    Vim9: no proper error for nested ":def!".
Solution:   Check for "!". (closes #6920)
diff --git a/src/version.c b/src/version.c
index 7aa35c2..5386822 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1657,
+/**/
     1656,
 /**/
     1655,