patch 8.2.1036: popupwin test fails sometimes

Problem:    Popupwin test fails sometimes.
Solution:   Use WaitForAssert() instead of a sleep.
diff --git a/src/testdir/test_popupwin.vim b/src/testdir/test_popupwin.vim
index 42f4256..80a1459 100644
--- a/src/testdir/test_popupwin.vim
+++ b/src/testdir/test_popupwin.vim
@@ -2454,9 +2454,11 @@
   call term_sendkeys(termbuf2, "exit\<CR>")
 
   " Exiting shell closes popup window
+  let pupwin = win_getid()
   call feedkeys("exit\<CR>", 'xt')
   " Wait for shell to exit
-  sleep 100m
+  call WaitForAssert({-> assert_notequal(pupwin, win_getid())})
+
   call feedkeys(":quit\<CR>", 'xt')
   call assert_equal(origwin, win_getid())
 endfunc
diff --git a/src/version.c b/src/version.c
index 3c6b744..42c03d0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1036,
+/**/
     1035,
 /**/
     1034,