Fix ssh on nixos

nix/modules/nixos/common.nix

@@ -21,11 +21,11 @@
   };
 
   programs.zsh.enable = true;
+  programs.ssh.startAgent = true;
 
   nix.settings = {
     experimental-features = [ "nix-command" "flakes" ];
     auto-optimise-store = true;
-    use-ssh-config = true;
   };
 
   nixpkgs.config.allowUnfree = true;