patch 8.2.1273: MS-Windows: terminal test may leave file behind

Problem:    MS-Windows: terminal test may leave file behind.
Solution:   Wait a moment for process to end before deleting the file.
            (Taro Muraoka, closes #6513)
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 067fa0f..fcc1156 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -808,6 +808,13 @@
   endif
   let g:job = term_getjob(buf)
   call WaitForAssert({-> assert_equal("dead", job_status(g:job))})
+
+  if has('win32')
+    " On Windows we cannot delete a file being used by a process.  When
+    " job_status() returns "dead", the process remains for a short time.
+    " Just wait for a moment.
+    sleep 50m
+  endif
   call delete('Xfile')
   bwipe