chore: Format with nixpkgs-fmt

Note that we will continue to use nixpkgs-fmt for the time being here
since nixfmt-rfc-style breaks string syntax highlighting and comments
like `/* this */` get turned into `# this`.

The conversion from lisp-like formatting to something else in flake.nix
is a bit unfortunate, but I'd rather have a singular style for the
entire code base to make things easier.

modules/system.nix

@@ -45,7 +45,8 @@ in
 
   config = {
     boot = {
-      tmp = if iHaveLotsOfRam
+      tmp =
+        if iHaveLotsOfRam
         then { useTmpfs = true; }
         else { cleanOnBoot = true; };