Function unban_user_handler 

async fn unban_user_handler(
    __arg0: State<ServerState>,
    __arg1: AuthenticatedClientRequest<Request>,
) -> Result<ArminiusResponse<Response>, InviteUserError>

Handler for POST /_matrix/client/v3/rooms/{roomId}/unban (See https://spec.matrix.org/v1.18/client-server-api/#post_matrixclientv3roomsroomidunban).

This endpoint is used to unban a user from a room