Use iog's cache and switch to install-nix-action

Author: spencerjanssen

.github/workflows/nix-integration-test.yml

@@ -14,5 +14,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@0c366fd6a839edf440554fa01a7085ccba70ac98 # v4.1.1
-      - uses: DeterminateSystems/nix-installer-action@786fff0690178f1234e4e1fe9b536e94f5433196 # v20
+      - uses: cachix/install-nix-action@4e002c8ec80594ecd40e759629461e26c8abed15 # v31.9.0
+        with:
+          extra_nix_config: |
+            extra-trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
+            extra-substituters = https://cache.iog.io
       - run: nix flake check