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/shell.nix

@@ -47,7 +47,7 @@ in
           colorpanes
           sanctity
           cmatrix
-        ;
+          ;
       })
       (attrValues {
         inherit (pkgs)
@@ -55,7 +55,7 @@ in
           hexyl
           visidata
           zellij
-        ;
+          ;
       })
 
       (attrValues {
@@ -64,7 +64,7 @@ in
           unar
           rsync
           rclone
-        ;
+          ;
       })
 
       (mkIf postgres (attrValues {