Fix SPDX-License-Identifier annotation

[robinkrahl]

libnitrokey uses the SPDX-License-Identifier: LGPL-3.0 annotation, but the LGPL-3.0 identifier has been deprecated acording to this list. The identifier should be LGPL-3.0-or-later instead.

[szszszsz]

To be set as LGPL-3.0-only.

[dvzrv]

Hi! 👋

We've recently switched to making use of reuse in our package sources on Arch Linux.
I'm met with this discrepancy as well, due to a bug (or feature?) in reuse, that detects the SPDX license identifier annotation in my patch file as LGPL-3.0 (LGPL-3.0-only).
In your meson.build file you state that this project is licensed under the terms of LGPL-3.0+ (LGPL-3.0-or-later) though.

It would be really great to clean this up and make a new release.

Judging from the above comment, I gather though, that everything should be LGPL-3.0-only and not LGPL-3.0-or-later (as I wrongly assumed).

[robin-nitrokey]

@jans23 Can you please confirm that the license for libnitrokey should be LGPL-3.0-only?