patch 8.1.2256: test for ":term ++shell" fails on MS-Windows

Problem:    Test for ":term ++shell" fails on MS-Windows.
Solution:   Accept failure of "dir" executable.
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index ba17959..10e1075 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -2227,7 +2227,7 @@
   elseif has('win32')
     " dir is a shell builtin command, should fail without a shell.
     term dir /b runtest.vim
-    call WaitForAssert({-> assert_match('job failed', term_getline(bufnr(), 1))})
+    call WaitForAssert({-> assert_match('job failed\|cannot access .*: No such file or directory', term_getline(bufnr(), 1))})
     bwipe!
 
     term ++shell dir /b runtest.vim