Fix broken span test.

close #3
diff --git a/times_test.go b/times_test.go
index 0e202ae..dfa0d50 100644
--- a/times_test.go
+++ b/times_test.go
@@ -31,7 +31,7 @@
 		"1 week ago",
 		"2 weeks ago",
 		"1 month ago",
-		"3 month ago",
+		"3 months ago",
 		"1 year ago",
 	}