Update Nix

.github/workflows/nix.yml

@@ -0,0 +1,34 @@
+name: Nix
+
+on:
+  push:
+
+jobs:
+  shell:
+    strategy:
+      fail-fast: false
+      matrix:
+        platform:
+          - os: darwin
+            cpu: x86_64
+            base: macos-12
+          - os: linux
+            cpu: x86_64
+            base: ubuntu-22.04
+          - os: linux
+            cpu: aarch64
+            base: arm-4core-linux
+
+    name: Test Nix shell (${{ matrix.platform.cpu }}-${{ matrix.platform.os }})
+    runs-on: ${{ matrix.platform.base }}
+
+    permissions:
+      contents: read
+      id-token: write
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - run: nix-shell --run 'which ruby'
+      - run: nix-shell --run 'ruby --version'

shell.nix

@@ -1,9 +1,9 @@
 {
   pkgs ? import <nixpkgs> {},
-  pinned ? import(fetchTarball("https://github.com/NixOS/nixpkgs/archive/d7f206b723e4.tar.gz")) {},
+  pinned ? import(fetchTarball("https://github.com/NixOS/nixpkgs/archive/25865a40d14b.tar.gz")) {},
 }:
 let
-  ruby = pinned.ruby_3_2;
+  ruby = pinned.ruby_3_3;
   llvm = pinned.llvmPackages_16;
 in llvm.stdenv.mkDerivation {
   name = "shell";