patch 8.2.1139: Vim9: test for silent echo fails in some environments

Problem:    Vim9: test for silent echo fails in some environments.
Solution:   Use :function instead of :def.
diff --git a/src/version.c b/src/version.c
index 950871e..23d2d1b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1139,
+/**/
     1138,
 /**/
     1137,