Remove: nixfmt

Currently using alejandra for now, this isn't needed

fixes the following warning:

trace: warning: nixfmt was renamed to nixfmt-classic. The nixfmt attribute may be used for the new RFC 166-style formatter in the future, which is currently available as nixfmt-rfc-style

More details in:

NixOS/nixfmt#153

hosts/galvatron-wsl/configuration.nix

@@ -129,7 +129,6 @@
  gotools
  multimarkdown
  nil
- nixfmt
  pandoc
  shfmt
  shellcheck