Spam wave expiration validation to <= 368.day.from_now

The way we've been using spam waves has changed over the years.
While the default creation length remains 1 day and "renew"
remains 2 days, there are multiple spam waves which we are
keeping active continuously, and have done so for years. I'm
quite tired of having the daily task of renewing them, as I've
been doing nearly every day for a couple/few years now. This
change will allow manually editing the expiration time to
1 year in the future from any automated (i.e., 1 or 2 day)
date.

app/models/spam_wave.rb

@@ -124,7 +124,7 @@ def check_min_accuracy
   end
 
   def max_expiry
-    return if expiry <= 2.day.from_now
+    return if expiry <= 368.day.from_now
     errors.add(:expiry, 'must be no more than 48 hours from now')
   end
 end