patch 8.1.2151: state test is a bit flaky

Problem:    State test is a bit flaky.
Solution:   Add to the list of flaky tests.
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index e1ea7f1..a8eb5e2 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -341,6 +341,7 @@
       \ 'Test_raw_one_time_callback()',
       \ 'Test_reltime()',
       \ 'Test_server_crash()',
+      \ 'Test_state()',
       \ 'Test_term_mouse_double_click_to_create_tab()',
       \ 'Test_terminal_ansicolors_default()',
       \ 'Test_terminal_ansicolors_func()',