chore: update nixpkgs, use more recent ocamlformat

Author: W95Psp

engine/.ocamlformat

@@ -1,2 +1,2 @@
 profile = default
-version = 0.26.2
+version = 0.27.0

flake.lock

@@ -2,10 +2,7 @@
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs";
     flake-utils.url = "github:numtide/flake-utils";
-    crane = {
-      url = "github:ipetkov/crane";
-      inputs = { nixpkgs.follows = "nixpkgs"; };
-    };
+    crane = { url = "github:ipetkov/crane"; };
     rust-overlay = {
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -50,7 +47,6 @@
             });
         in rustc);
         craneLib = (crane.mkLib pkgs).overrideToolchain rustc;
-        ocamlformat = pkgs.ocamlformat_0_26_2;
         rustfmt = pkgs.rustfmt;
         fstar = inputs.fstar.packages.${system}.default;
         hax-env-file = pkgs.writeText "hax-env-file" ''
@@ -66,6 +62,7 @@
           fi
         '';
         ocamlPackages = pkgs.ocamlPackages;
+        ocamlformat = ocamlPackages.ocamlformat_0_27_0;
       in rec {
         packages = {
           inherit rustc ocamlformat rustfmt fstar hax-env rustc-docs;