Revert "ci: test building demeter image"

This reverts commit ba022c35b7.

.github/workflows/main.yml

@@ -14,5 +14,5 @@ jobs:
       with:
         name: liminalos
         # If you chose API tokens for write access OR if you have a private cache
-          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
-      - run: nix build .#demeter --accept-flake-config
+        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+    - run: nix build

flake.nix

@@ -190,10 +190,4 @@
       ];
     };
   };
-
-  nixConfig = {
-    extra-substituters = ["https://liminalos.cachix.org"];
-    extra-trusted-public-keys = ["liminalos.cachix.org-1:GpwgIRFfXwZtZaHA2RPaVGI2ErJKasbb15pkMmQ7dN4="];
-    allow-import-from-derivation = "true";
-  };
 }