patch 8.2.3137: Vim9: no error when a line only has a variable name

Problem:    Vim9: no error when a line only has a variable name.
Solution:   Give an error when an expression is evaluated without an effect.
            (closes #8538)
diff --git a/src/version.c b/src/version.c
index bcbff0a..762f3f8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3137,
+/**/
     3136,
 /**/
     3135,