patch 9.0.1831: Vim9: failing null test

Problem:  Vim9: failing null test
Solution: Use required public keyword

closes: #12982

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Gianmaria Bajo <mg1979.git@gmail.com>
diff --git a/src/version.c b/src/version.c
index 3aa10c6..12979e6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1831,
+/**/
     1830,
 /**/
     1829,