Breaking change in cypto overlay and a fix

[bladyjoker]

After ee5f5b0#diff-206b9ce276ab5971a2489d75eb1b12999d4bf3843b7988cbe8d687cfde61dea0R16 you might have experienced breakage like we did.

error: value is a function while a set was expected

       at «none»:0: (source not available)

To fix do the following...

In your flake.nix inputs use iohk-nix repo as a flake if you didn't already

-    iohk-nix = { url = "github:input-output-hk/iohk-nix"; flake = false; };
+    iohk-nix.url = "github:input-output-hk/iohk-nix";

And change the way you add the crypto overlay

-              (import "${iohk-nix}/overlays/crypto")
+              inputs.iohk-nix.overlays.crypto