evtx: use sys.maxsize over maxint

thanks to @goorgoorlou in #52

Author: williballenthin

Evtx/Evtx.py

@@ -229,7 +229,7 @@ def chunks(self, include_inactive=False):
         declared in the file header (and may therefore be corrupt).
         """
         if include_inactive:
-            chunk_count = sys.maxint
+            chunk_count = sys.maxsize
         else:
             chunk_count = self.chunk_count()