patch 8.2.0520: tests are not listed in sorted order

Problem:    Tests are not listed in sorted order.
Solution:   Move test_ex_mode. (Doug Richardson, closes #5889)

src/testdir/Make_all.mak

@@ -96,9 +96,9 @@ NEW_TESTS = \
 	test_escaped_glob \
 	test_eval_stuff \
 	test_ex_equal \
+	test_ex_mode \
 	test_ex_undo \
 	test_ex_z \
-	test_ex_mode \
 	test_excmd \
 	test_exec_while_if \
 	test_execute_func \

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    520,
 /**/
     519,
 /**/