patch 9.1.0721: tests: test_mksession does not consider XDG_CONFIG_HOME

Problem:  tests: test_mksession does not consider XDG_CONFIG_HOME
Solution: allow to match $HOME/.vim/ and $HOME/.config/vim for &viewdir
          (John M Devin)

closes: #15639

Signed-off-by: John M Devin <john.m.devin@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 5c3c5ef..eb88b0d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    721,
+/**/
     720,
 /**/
     719,