patch 8.2.0277: Vim9: not all instructions covered by tests

Problem:    Vim9: not all instructions covered by tests.
Solution:   Add more test cases.
diff --git a/src/version.c b/src/version.c
index 5095de4..b76a354 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    277,
+/**/
     276,
 /**/
     275,