nix: revert from ghc927 to ghc926

 since support for 9.2.7 is not yet merged in haskell.nix master.

Author: jbgi

flake.lock

@@ -14,10 +14,6 @@
       url = "github:input-output-hk/hackage.nix";
       flake = false;
     };
-    nixTools = {
-      url = "github:input-output-hk/nix-tools";
-      flake = false;
-    };
     haskellNix = {
       url = "github:input-output-hk/haskell.nix";
       inputs.nixpkgs.follows = "nixpkgs";

flake.nix

@@ -21,7 +21,7 @@ let
       name = "cardano-node";
       compiler-nix-name = lib.mkDefault "ghc8107";
       # extra-compilers
-      flake.variants = lib.genAttrs ["ghc927"] (x: {compiler-nix-name = x;});
+      flake.variants = lib.genAttrs ["ghc926"] (x: {compiler-nix-name = x;});
       cabalProjectLocal = ''
         allow-newer: terminfo:base
       '' + lib.optionalString pkgs.stdenv.hostPlatform.isWindows ''