fix: do not copy client

If we copy the client, some bound models that where created during the cached session, will still hold  the reference to the cached_client, even outside the scope of the context manager.

By not copying the client, we ensure that the bound model client is not caching request outside the scope of the context.

hcloud/_client.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import copy
 import time
 from contextlib import contextmanager
 from typing import Generator, NoReturn
@@ -251,9 +250,9 @@ def cached_session(self) -> Generator[Client, None, None]:
         Cached response will not expire, therefore the cached client must not be used
         for long living scopes.
         """
-        client = copy.deepcopy(self)
-        client.session(CachedSession())
-        yield client
+        self.session(CachedSession())
+        yield self
+        self.session(requests.Session())
 
 
 class CachedSession(requests.Session):