This is the result of executing:
git mv -f pkgs/applications/window-managers/sway/beta.nix pkgs/applications/window-managers/sway/default.nix
git mv -f nixos/modules/programs/sway-beta.nix nixos/modules/programs/sway.nix
And removing sway-beta from the following files:
pkgs/top-level/all-packages.nix
nixos/modules/module-list.nix