update actions+flake

Author: Anton-4

Diff for: .github/workflows/tests.yml

@@ -12,7 +12,7 @@ jobs:
         operating-system: [ubuntu-22.04, ubuntu-24.04, ubuntu-24.04-arm, macos-13, macos-14]
     timeout-minutes: 90
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set OS-specific variables
         id: vars

Diff for: .github/workflows/tests_nix.yml

@@ -13,14 +13,14 @@ jobs:
     test-examples:
         runs-on: [ubuntu-22.04]
         steps:
-            - uses: actions/checkout@v3
+            - uses: actions/checkout@v4
 
             # install nix
-            - uses: cachix/install-nix-action@v23
+            - uses: cachix/install-nix-action@02a151ada4993995686f9ed4f1be7cfbb229e56f # commit for v31
               with:
                 nix_path: nixpkgs=channel:nixos-unstable
 
-            - uses: cachix/cachix-action@v12
+            - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # commit for v16
               with:
                   name: enigmaticsunrise
                   authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'