patch 9.0.2057: Vim9: no strict type checks for funcrefs varargs

Problem:  Vim9: no strict type checks for funcrefs varargs
Solution: Perform strict type checking when declaring funcrefs
          with vararg declaration, add tests

closes: #13397

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ernie Rael <errael@raelity.com>
diff --git a/src/version.c b/src/version.c
index 7584e45..fbf2999 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2057,
+/**/
     2056,
 /**/
     2055,