lib.licenses: add Parity-7.0.0 license

[fabianhjr]

Motivation for this change

Adds Parity-7.0.0 which was recently added to SPDX over at spdx/license-list-XML#949.

See https://paritylicense.com for more information.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• 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 nixpkgs-review --run "nixpkgs-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)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[fabianhjr]

@ghuntley

Before merging, I am unsure if this would be considered a free or non-free license.

[ghuntley]

Gut feels: free, as in it doesn't restrict who can use it. It does require contribution back under certain circumstances such as AGPL. Worth dinging some other folks and getting their opinions as well.

[vikanezrimaya]

Well, it's a "free for open source or personal use" license as it seems to me. If you share your work, you can do anything. If GPL is free with conditions (provide source code if you distribute or build upon), then this should probably be a free license too.