patch 9.0.0546: supporting Ruby 1.8 makes code complicated

Problem:    Supporting Ruby 1.8 makes code complicated.
Solution:   Drop Ruby 1.8 support, it is ancient. (Ken Takata, closes #11195)
diff --git a/src/version.c b/src/version.c
index 196b9d8..4641a1f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    546,
+/**/
     545,
 /**/
     544,