FIX: enable update period check

For debugging purposes, this check was disabled and unintentionally not
reenabled

euroexchange/euroexchange.py

@@ -268,8 +268,6 @@ class EuroExchangeBot( pywikibot.bot.BaseBot ):
         @rtype bool
         """
 
-        return True
-
         # Get datetime of last update
         last_update = self.current_job.filepage.latest_file_info.timestamp