CI: disable the test_terminal_resize() test for GH CI in GUI (#13603)

fixes: #13566

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_terminal2.vim

@@ -247,7 +247,11 @@ endfunc
 
 " Resizing the terminal window caused an ml_get error.
 " TODO: This does not reproduce the original problem.
+" TODO: This test starts timing out in Github CI Gui test, why????
 func Test_terminal_resize()
+  if has('gui_running') && expand('$GITHUB_ACTIONS') ==# 'true'
+    throw 'Skipped: FIXME: this test times-out in Github Actions CI with GUI. Why?'
+  endif
   set statusline=x
   terminal
   call assert_equal(2, winnr('$'))