Merge pull request #128 from EspressoSystems/dependabot/github_actions/cachix/install-nix-action-21

Bump cachix/install-nix-action from 20 to 21

.github/workflows/build_nix.yml

@@ -17,7 +17,7 @@ jobs:
           access_token: ${{ github.token }}
 
       - name: Install Nix
-        uses: cachix/install-nix-action@v20
+        uses: cachix/install-nix-action@v21
 
       - name: Checkout Repository
         uses: actions/checkout@v3