Merge pull request #127 from EspressoSystems/dependabot/github_actions/cachix/install-nix-action-20

Bump cachix/install-nix-action from 18 to 20

.github/workflows/build_nix.yml

@@ -17,7 +17,7 @@ jobs:
           access_token: ${{ github.token }}
 
       - name: Install Nix
-        uses: cachix/install-nix-action@v18
+        uses: cachix/install-nix-action@v20
 
       - name: Checkout Repository
         uses: actions/checkout@v3