patch 8.2.0303: TermChanged test fails in the GUI

Problem:    TermChanged test fails in the GUI.
Solution:   Skip the test when running the GUI.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 70e9608..2ff231d 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -2387,6 +2387,8 @@
 endfunc
 
 func Test_TermChanged()
+  CheckNotGui
+
   enew!
   tabnew
   call setline(1, ['a', 'b', 'c', 'd'])