Server: Use max() instead of if

* Silences a pylint warning.

warden_server/warden_server.py

@@ -1777,7 +1777,7 @@ class WardenHandler(ObjectBase):
         if id <= 0:
             # Client wants to get only last N events and reset server notion of last id
             id += self.db.getLastEventId()
-            if id < 0: id = 0
+            id = max(id, 0)
 
         try:
             count = int(count[0])