Do not redirect on 304 for aiohttp

vcr/stubs/aiohttp_stubs/__init__.py

@@ -92,6 +92,9 @@ def play_responses(cassette, vcr_request):
     # If we're following redirects, continue playing until we reach
     # our final destination.
     while 300 <= response.status <= 399:
+        if "location" not in response.headers:
+            break
+
         next_url = URL(response.url).with_path(response.headers["location"])
 
         # Make a stub VCR request that we can then use to look up the recorded