.github: improve nix build output

Author: nikstur

.github/workflows/ci.yml

@@ -11,8 +11,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: cachix/install-nix-action@v26
-      - uses: DeterminateSystems/magic-nix-cache-action@v4
+      - uses: DeterminateSystems/nix-installer-action@v13
         with:
           diagnostic-endpoint: ""
-      - run: nix flake check
+          source-url: "https://install.lix.systems/lix/lix-installer-x86_64-linux"
+      - uses: DeterminateSystems/magic-nix-cache-action@v7
+        with:
+          diagnostic-endpoint: ""
+      - run: nix flake check --log-format raw-with-logs -L
+
+env:
+  FORCE_COLOR: 1