Fix memory issues with webhooks. (#570)

* Update sync.py

* Update async_.py

Author: izxxr

discord/webhook/async_.py

@@ -29,6 +29,7 @@
 import asyncio
 import json
 import re
+import weakref
 
 from urllib.parse import quote as urlquote
 from typing import Any, Dict, List, Literal, NamedTuple, Optional, TYPE_CHECKING, Tuple, Union, overload
@@ -98,7 +99,7 @@ async def __aexit__(self, type, value, traceback):
 
 class AsyncWebhookAdapter:
     def __init__(self):
-        self._locks: Dict[Any, asyncio.Lock] = {}
+        self._locks: weakref.WeakValueDictionary = weakref.WeakValueDictionary()
 
     async def request(
         self,

discord/webhook/sync.py

@@ -36,6 +36,7 @@
 import json
 import time
 import re
+import weakref
 
 from urllib.parse import quote as urlquote
 from typing import Any, Dict, List, Literal, Optional, TYPE_CHECKING, Tuple, Type, TypeVar, Union, overload
@@ -94,7 +95,7 @@ def __exit__(self, type, value, traceback):
 
 class WebhookAdapter:
     def __init__(self):
-        self._locks: Dict[Any, threading.Lock] = {}
+        self._locks: weakref.WeakValueDictionary = weakref.WeakValueDictionary()
 
     def request(
         self,