updated for version 7.3.721

Problem:    Ruby interface defines local functions globally.
Solution:   Make the functions static.

src/version.c

@@ -725,6 +725,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    721,
 /**/
     720,
 /**/