update cachix CI action

.github/workflows/nix-flake-check.yml

@@ -7,20 +7,19 @@ on:
 
 jobs:
   checks:
-    name: Checks
+    name: "Checks"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: cachix/install-nix-action@v19
-        with:
-          nix_path: nixpkgs=channel:nixos-stable
-          extra_nix_config: |
-            experimental-features = nix-command flakes
-            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
-            system-features = nixos-test benchmark big-parallel kvm
-      - uses: cachix/cachix-action@v12
-        with:
-          name: dadada
-          authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-      - name: Checks
-        run: nix flake check
+    - uses: actions/checkout@v3
+    - uses: cachix/install-nix-action@v20
+      with:
+        nix_path: nixpkgs=channel:nixos-unstable
+    - uses: cachix/cachix-action@v12
+      with:
+        name: mycache
+        # If you chose signing key for write access
+        signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
+        # If you chose API tokens for write access OR if you have a private cache
+        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+    - run: nix-build
+    - run: nix-shell --run "echo OK"