Deleted date range in the spdx to match style of the project

Signed-off-by: Leonardo Carreras <leonardo.carreras@eonerc.rwth-aachen.de>

pyproject.toml

-# SPDX-FileCopyrightText: 2017-2023, Institute for Automation of Complex Power Systems, EONERC, RWTH Aachen University
+# SPDX-FileCopyrightText: 2023, Institute for Automation of Complex Power Systems, EONERC, RWTH Aachen University
 # SPDX-License-Identifier: Apache-2.0
 
 [build-system]