patch 9.0.0331: cannot use items() on a string

Problem:    Cannot use items() on a string.
Solution:   Make items() work on a string. (closes #11016)
diff --git a/src/version.c b/src/version.c
index 87881f1..2f409cf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -708,6 +708,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    331,
+/**/
     330,
 /**/
     329,