updated for version 7.3.620

Problem:    Building with recent Ruby on Win32 doesn't work.
Solution:   Add a separate argument for the API version. (Yasuhiro Matsumoto)

src/version.c

@@ -714,6 +714,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    620,
 /**/
     619,
 /**/