patch 8.1.0924: terminal scrollback test still flaky

Problem:    Terminal scrollback test still flaky.
Solution:   Wait a bit longer before running the tail command.

src/testdir/test_terminal.vim

@@ -311,9 +311,9 @@ func Test_terminal_postponed_scrollback()
   call writefile(range(50), 'Xtext')
   call writefile([
 	\ 'terminal',
-	\ 'sleep 100m',
+	\ 'sleep 400m',
 	\ 'call feedkeys("tail -n 100 -f Xtext\<CR>", "xt")',
-	\ 'sleep 100m',
+	\ 'sleep 200m',
 	\ 'call feedkeys("\<C-W>N", "xt")',
 	\ ], 'XTest_postponed')
   let buf = RunVimInTerminal('-S XTest_postponed', {})

src/version.c

@@ -783,6 +783,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    924,
 /**/
     923,
 /**/