bugfix: threading id means nothing for async, use loop id

- Asynchronous code making use of a threading ``id`` for the cache key
  doesn't make as much sense as using a loop ``id``. Running the core
  tests with ``pytest-xdist`` runners actually seems to have identified
  a bug in this code that was previously well hidden. Replace the threading
  id with loop id when generating unique cache keys in the http session
  manager.

Author: fselmo

web3/_utils/http_session_manager.py

@@ -178,7 +178,7 @@ async def async_cache_and_return_session(
         request_timeout: Optional[ClientTimeout] = None,
     ) -> ClientSession:
         # cache key should have a unique thread identifier
-        cache_key = generate_cache_key(f"{threading.get_ident()}:{endpoint_uri}")
+        cache_key = generate_cache_key(f"{id(asyncio.get_event_loop())}:{endpoint_uri}")
 
         evicted_items = None
         async with async_lock(self.session_pool, self._lock):