Avoid can't compare offset-naive and offset-aware datetimes in is_e…

…xpired check for CachedResponse.

aiohttp_client_cache/response.py

@@ -159,7 +159,7 @@ def host(self) -> str:
     def is_expired(self) -> bool:
         """Determine if this cached response is expired"""
         try:
-            return self.expires is not None and utcnow() > self.expires
+            return self.expires is not None and utcnow() > self.expires.replace(tzinfo=None)
         except (AttributeError, TypeError, ValueError):
             # Consider it expired and fetch a new response
             return True