Replace DeterminateSystems/nix-installer with official installer (#400)

Author: kachick

.github/dependabot.yml

@@ -6,10 +6,6 @@ updates:
       interval: 'monthly'
     ignore:
       - dependency-name: 'crate-ci/typos'
-    groups:
-      nix-actions:
-        patterns:
-          - 'DeterminateSystems*'
   - package-ecosystem: 'bundler'
     # Don't icnlude '/gemfiles/oldest', the gemspec is not parsible by dependabot and using hardlink will broken the require_relative in gemspec
     directory: '/'

.github/workflows/ci-nix.yml

@@ -26,7 +26,11 @@ jobs:
     timeout-minutes: 30
     steps:
       - uses: actions/checkout@v5
-      - uses: DeterminateSystems/nix-installer-action@v20
+      - uses: cachix/install-nix-action@7ec16f2c061ab07b235a7245e06ed46fe9a1cab6 # v31.8.3
+        with:
+          extra_nix_config: |
+            sandbox = true
+            accept-flake-config = true
       - run: nix flake check
       - run: nix develop --command echo 'This step should be done before any other "nix develop" steps because of measuring Nix build time'
       - run: nix develop --command bundle install

.github/workflows/merge-bot-pr.yml

@@ -29,7 +29,7 @@ jobs:
             ]
         timeout-minutes: 10
       - name: Approve and merge
-        if: ${{ (steps.metadata.outputs.update-type != 'version-update:semver-major') || contains(steps.metadata.outputs.dependency-names, 'DeterminateSystems') }}
+        if: ${{ (steps.metadata.outputs.update-type != 'version-update:semver-major') || contains(steps.metadata.outputs.dependency-names, 'cachix') }}
         run: gh pr review --approve "$PR_URL" && gh pr merge --auto --squash --delete-branch "$PR_URL"
         env:
           PR_URL: ${{ github.event.pull_request.html_url }}

CONTRIBUTING.md

@@ -4,7 +4,7 @@
 
 If only changing Ruby code, this step is unnecessary
 
-1. Install [Nix](https://nixos.org/) package manager and enable [Flakes](https://nixos.wiki/wiki/Flakes)\
+1. Install [Nix](https://nixos.org/) package manager and enable [Flakes](https://wiki.nixos.org/wiki/Flakes)\
    Or use Nix installed containers. For example, look at [this repo](https://github.com/kachick/containers)
 2. Run dev shell as one of the following
    - with [direnv](https://github.com/direnv/direnv): `direnv allow`