patch 8.1.0533: screendump tests can be flaky

Problem:    Screendump tests can be flaky.
Solution:   Add VerifyScreenDump to the pattern of flaky tests.
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index 9ba5d13..56bb3d3 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -330,7 +330,7 @@
       \ ]
 
 " Pattern indicating a common flaky test failure.
-let s:flaky_errors_re = 'StopVimInTerminal'
+let s:flaky_errors_re = 'StopVimInTerminal\|VerifyScreenDump'
 
 " Locate Test_ functions and execute them.
 redir @q
diff --git a/src/version.c b/src/version.c
index f6be0c0..560abd4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    533,
+/**/
     532,
 /**/
     531,