[Bugfix] Fix for the anonymous user’s timezone

It returned `None` instead of the application default.

calsocial/security.py

@@ -17,6 +17,7 @@
 """Security related things for Calendar.social
 """
 
+from flask import current_app
 from flask_security import Security, AnonymousUser as BaseAnonymousUser
 
 security = Security()
@@ -31,4 +32,4 @@ class AnonymousUser(BaseAnonymousUser):
         """The time zone of the anonymous user
         """
 
-        return None
+        return current_app.timezone