Motivation for this change

See the bottom of https://spdx.org/licenses/ for the list of deprecations.

The explicit URLs of agpl3Plus and gpl2Classpath were dropped because the default SPDX URL is correct. wxWindows ID had wrong capitalization.

I have not updated the license IDs that were deprecated in favor of license expressions, e.g. GPL-2.0-with-classpath-exception → GPL-2.0-only WITH Classpath-exception-2.0 or wxWindows → LGPL-2.0-or-later WITH WxWindows-exception-3.1, because the former have a single URL and the latter need an URL for the license and an URL for the exception, and they are more complex.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.