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/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 8f11217..f537eef 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -209,6 +209,9 @@
 enddef
 
 def Test_ch_logfile()
+  if !has('channel')
+    CheckFeature channel
+  endif
   assert_fails('ch_logfile(true)', 'E1174')
   assert_fails('ch_logfile("foo", true)', 'E1174')
 enddef