force only IOG cache

Author: dermetfan

flake.nix

@@ -2,7 +2,7 @@
   description = "Cardano Node";
 
   nixConfig = {
-    extra-substituters = ["https://cache.iog.io" "https://hydra.iohk.io"];
+    substituters = ["https://cache.iog.io"];
     extra-trusted-public-keys = ["hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ="];
   };