chore(deps): update determinatesystems/nix-installer-action action to v20

Author: renovate[bot]

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@v19
+        uses: DeterminateSystems/nix-installer-action@v20
 
       - name: Setup Nix cache
         uses: DeterminateSystems/magic-nix-cache-action@v13