patch 8.1.0331: insufficient test coverage for :mkview and :loadview

Problem:    Insufficient test coverage for :mkview and :loadview.
Solution:   Add tests. (Dominique Pelle, closes #3385)
diff --git a/src/version.c b/src/version.c
index f02b9f9..e2123eb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    331,
+/**/
     330,
 /**/
     329,