update rankings date update parsing logic.

lib/ncaa/parser/html/rankings.rb

@@ -32,10 +32,13 @@ module Ncaa
 
         # @return [Time]
         def last_updated
-          @last_updated ||= begin
+          @last_updated ||=
+            begin
               updated = html.css('figure.rankings-last-updated').text
-            date = updated[/\w+{3,}\.? \d+{1,2}, \d+{2,4}/]
+              date = updated[/\w+{3,}\.? \d+{1,2}\,? \d+{2,4}/]
               Time.parse(date)
+            rescue TypeError
+              nil
             end
         end