Use packages

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

lib/fetchers/default.nix

@@ -1,4 +1,7 @@
 { pkgs, ... }:
+let
+  callPackage = pkgs.lib.callPackageWith { inherit pkgs; };
+in
 {
-  sshKnownHosts = import ./sshKnownHosts { inherit pkgs; };
+  sshKnownHosts = callPackage ./sshKnownHosts { };
 }