update type annotations

Author: atstaeff

eventsourcingdb/client.py

@@ -30,10 +30,10 @@ def __init__(
         self,
         base_url: str,
         api_token: str,
-    ):
+    ) -> None:
         self.__http_client = HttpClient(base_url=base_url, api_token=api_token)
 
-    async def __aenter__(self) -> "Client":
+    async def __aenter__(self) -> 'Client':
         await self.__http_client.__aenter__()
         return self