patch 8.1.0922: terminal scrollback test is flaky

Problem:    Terminal scrollback test is flaky.
Solution:   Wait a bit before running the tail command.
diff --git a/src/version.c b/src/version.c
index d0857e7..bf47f97 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    922,
+/**/
     921,
 /**/
     920,