style: Switch to nixfmt from nixpkgs-fmt

Most of the ecosystem has moved to this formatter,
and many people configured their editors to autoformat it with this formatter.

Closes: https://git.snix.dev/snix/snix/issues/62
Change-Id: Icf39e7836c91fc2ae49fbe22a40a639105bfb0bd
Reviewed-on: https://cl.snix.dev/c/snix/+/30671
Reviewed-by: Florian Klink <flokli@flokli.de>
Tested-by: besadii
Autosubmit: Ilan Joselevich <personal@ilanjoselevich.com>

contrib/snixbolt/default.nix

@@ -1,4 +1,9 @@
-{ pkgs, lib, depot, ... }:
+{
+  pkgs,
+  lib,
+  depot,
+  ...
+}:
 let
   pkgsCross = pkgs.pkgsCross.wasm32-unknown-none;
 in
@@ -8,25 +13,26 @@ in
       src = depot.snix.utils.filterRustCrateSrc { root = prev.src.origSrc; };
     };
   };
-}).rootCrate.build.overrideAttrs (oldAttrs: {
-  installPhase = ''
-    ${lib.getExe pkgs.wasm-bindgen-cli} \
-      --target web \
-      --out-dir $out \
-      --out-name ${oldAttrs.crateName} \
-      --no-typescript \
-      target/lib/${oldAttrs.crateName}-${oldAttrs.metadata}.wasm
+}).rootCrate.build.overrideAttrs
+  (oldAttrs: {
+    installPhase = ''
+      ${lib.getExe pkgs.wasm-bindgen-cli} \
+        --target web \
+        --out-dir $out \
+        --out-name ${oldAttrs.crateName} \
+        --no-typescript \
+        target/lib/${oldAttrs.crateName}-${oldAttrs.metadata}.wasm
 
-      mv src/*.{html,css} $out
-  '';
+        mv src/*.{html,css} $out
+    '';
 
-  passthru.serve = pkgs.writeShellScriptBin "snixbolt-serve" ''
-    ${lib.getExe pkgs.simple-http-server} \
-        --index \
-        --nocache \
-        "$@" \
-        ${depot.contrib.snixbolt}
-  '';
+    passthru.serve = pkgs.writeShellScriptBin "snixbolt-serve" ''
+      ${lib.getExe pkgs.simple-http-server} \
+          --index \
+          --nocache \
+          "$@" \
+          ${depot.contrib.snixbolt}
+    '';
 
-  meta.ci.extraSteps.crate2nix-check = depot.snix.utils.mkCrate2nixCheck ./Cargo.nix;
-})
+    meta.ci.extraSteps.crate2nix-check = depot.snix.utils.mkCrate2nixCheck ./Cargo.nix;
+  })