Switch from dep5 to REUSE.toml

.reuse/dep5

-Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
-Upstream-Name: mtime
-Upstream-Contact: Luis Kornblueh <luis.kornblueh@mpimet.mpg.de>
-Source: https://gitlab.dkrz.de/icon-libraries/libmtime
-
-Files: AUTHORS NEWS README */README
-Copyright: 2013-2024 MPI-M, Luis Kornblueh, Rahul Sinha and DWD, Florian Prill. All rights reserved.
-License: CC-BY-4.0
-
-Files: scripts/reconfigure
-Copyright: 2021 Thomas Jahns <jahns@dkrz.de>
-License: BSD-3-Clause
-
-Files: m4/acx_lt_problems.m4
-Copyright: 2011 Thomas Jahns <jahns@dkrz.de>
-License: BSD-3-Clause
-
-Files: m4/acx_use_libtool_configuration.m4
-Copyright: 2016 Thomas Jahns <jahns@dkrz.de>
-License: BSD-3-Clause
-
-Files: m4/kpse_libtool.m4
-Copyright:
-  1995 - 2009 Karl Berry <tex-live@tug.org>
-  2009, 2010 Peter Breitenlohner <tex-live@tug.org>
-License: FSFULLR
-
-Files: contrib/*/README.txt
-Copyright: 2024 Thomas Jahns <jahns@dkrz.de>
-License: CC-BY-4.0
-
-Files: contrib/*.patch
-Copyright: 2024 Thomas Jahns <jahns@dkrz.de>
-License: GPL-2.0-or-later WITH Libtool-exception

REUSE.toml

+# Copyright (c) 2013-2024 MPI-M, Luis Kornblueh, Rahul Sinha and DWD, Florian Prill. All rights reserved.
+#
+# SPDX-License-Identifier: CC0-1.0
+
+version = 1
+
+[[annotations]]
+path = ["AUTHORS", "NEWS", "**/README"]
+SPDX-FileCopyrightText = "2013-2024 MPI-M, Luis Kornblueh, Rahul Sinha and DWD, Florian Prill. All rights reserved."
+SPDX-License-Identifier = "CC-BY-4.0"
+
+[[annotations]]
+path = ["m4/acx_lt_problems.m4", "m4/acx_use_libtool_configuration.m4", "scripts/reconfigure"]
+SPDX-License-Identifier = "BSD-3-Clause"
+
+[[annotations]]
+path = "m4/kpse_libtool.m4"
+SPDX-License-Identifier = "FSFULLR"
+
+[[annotations]]
+path = "contrib/**/README.txt"
+SPDX-FileCopyrightText = "2024 Thomas Jahns <jahns@dkrz.de>"
+SPDX-License-Identifier = "CC-BY-4.0"
+
+[[annotations]]
+path = "contrib/**.patch"
+SPDX-FileCopyrightText = "2024 Thomas Jahns <jahns@dkrz.de>"
+SPDX-License-Identifier = "GPL-2.0-or-later WITH Libtool-exception"