patch 8.2.2715: Vim9: tests fail without the channel feature

Problem:    Vim9: tests fail without the channel feature. (Dominique Pellé)
Solution:   Check for the channel feature. (closes #8063)
diff --git a/src/version.c b/src/version.c
index 2d3368d..86b0593 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2715,
+/**/
     2714,
 /**/
     2713,