Resolve "Review tasks"

Closes #8 (closed)

aleksis/apps/matrix/util/matrix.py

 import time
 from json import JSONDecodeError
-from typing import Any, Dict, Optional
+from typing import Any, Optional
 from urllib.parse import urljoin
 
 import requests
@@ -24,7 +24,7 @@ def get_headers():
     }
 
 
-def do_matrix_request(method: str, url: str, body: Optional[dict] = None) -> Dict[str, Any]:
+def do_matrix_request(method: str, url: str, body: Optional[dict] = None) -> dict[str, Any]:
     """Do a HTTP request to the Matrix Client Server API."""
     while True:
         res = requests.request(method=method, url=build_url(url), headers=get_headers(), json=body)