patch 8.0.1453: terminal test fails on some slow terminals

Problem:    Terminal test fails on some slow terminals.
Solution:   Increase timeout to 10 seconds.
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 18d2815..0c2e289 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -522,7 +522,7 @@
   " On MS-Windows there is an extra empty line below "done".  Find "done" in
   " the last-but-one or the last-but-two line.
   let lnum = term_getsize(buf)[0] - 1
-  call WaitFor({-> term_getline(buf, lnum) =~ "done" || term_getline(buf, lnum - 1) =~ "done"}, 3000)
+  call WaitFor({-> term_getline(buf, lnum) =~ "done" || term_getline(buf, lnum - 1) =~ "done"}, 10000)
   let line = term_getline(buf, lnum)
   if line !~ 'done'
     let line = term_getline(buf, lnum - 1)