fix: [chat messages by year] fix subchannel nb_max

Author: Terrtia

bin/lib/objects/abstract_chat_object.py

@@ -262,6 +262,7 @@ def get_nb_year_messages(self, year):
                 if date not in nb_year:
                     nb_year[date] = 0
                 nb_year[date] += 1
+                nb_max = max(nb_max, nb_year[date])
 
         return nb_max, nb_year