patch 9.1.0571: tests: Test_gui_lowlevel_keyevent is flaky

Problem:  tests: Test_gui_lowlevel_keyevent is flaky
Solution: mark as flaky (Ken Takata)

Test_gui_lowlevel_keyevent is failing on vim-win32-installer recently.
Mark it as flaky for now.

closes: #15223

Signed-off-by: Ken Takata <kentkt@csc.jp>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_gui.vim b/src/testdir/test_gui.vim
index d53750f..eefebff 100644
--- a/src/testdir/test_gui.vim
+++ b/src/testdir/test_gui.vim
@@ -1706,6 +1706,7 @@
 func Test_gui_lowlevel_keyevent()
   CheckMSWindows
   new
+  let g:test_is_flaky = 1
 
   " Test for <Ctrl-A> to <Ctrl-Z> keys
   for kc in range(65, 90)
diff --git a/src/version.c b/src/version.c
index 2003f53..194099b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    571,
+/**/
     570,
 /**/
     569,