patch 9.0.1821: Vim9 constructors are always static

Problem:  Vim9 constructors are always static
Solution: make the "static" keyword an error

closes: #12945

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 c23c257..8f978f9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1821,
+/**/
     1820,
 /**/
     1819,