patch 8.2.2777: Vim9: blob operations not tested in all ways

Problem:    Vim9: blob operations not tested in all ways.
Solution:   Run tests with CheckLegacyAndVim9Success().  Make blob assign with
            index work.
diff --git a/src/version.c b/src/version.c
index e1f1526..17afa34 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2777,
+/**/
     2776,
 /**/
     2775,