Motivation for this change

• Added ligations for ==, !=, ===, !==, <=, >=, and /= for Haskell-like languages.
• Added a termlig building directive for term-width variant but with ligations.
• Added ability to customize font menu family name and target weights when building.

Source: https://github.com/be5invis/Iosevka/releases/tag/v1.14.0

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-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/)
• Fits CONTRIBUTING.md.