Fix comment: date is a simple string.

apachedex/__init__.py

@@ -271,7 +271,7 @@ class ERP5SiteStats(GenericSiteStats):
     # Key levels:
     # - module id (string)
     # - is document (bool)
-    # - date (datetime.date)
+    # - date (string)
     self.module = defaultdict(partial(defaultdict, partial(
       defaultdict, partial(APDEXStats, threshold, getDuration))))
     self.no_module = defaultdict(partial(APDEXStats, threshold, getDuration))