fix python lint errors

Author: Simon-Laux

deltachat-rpc-client/tests/test_chatlist_events.py

@@ -1,7 +1,5 @@
 from __future__ import annotations
 
-import base64
-import os
 from typing import TYPE_CHECKING
 
 from deltachat_rpc_client import Account, EventType, const

deltachat-rpc-client/tests/test_something.py

@@ -11,7 +11,7 @@
 import pytest
 
 from deltachat_rpc_client import Contact, EventType, Message, events
-from deltachat_rpc_client.const import ChatType, DownloadState, MessageState
+from deltachat_rpc_client.const import ChatType, MessageState
 from deltachat_rpc_client.pytestplugin import E2EE_INFO_MSGS
 from deltachat_rpc_client.rpc import JsonRpcError