cynthion: remove amaranth version override

pkgs/by-name/cy/cynthion/package.nix

···
 {
   python3,
-  fetchFromGitHub,
 }:
 
-let
-  python = python3.override {
-    self = python3;
-    packageOverrides = _: super: {
-      amaranth = super.amaranth.overridePythonAttrs rec {
-        version = "0.4.1";
-
-        src = fetchFromGitHub {
-          owner = "amaranth-lang";
-          repo = "amaranth";
-          rev = "refs/tags/v${version}";
-          sha256 = "sha256-VMgycvxkphdpWIib7aZwh588En145RgYlG2Zfi6nnDo=";
-        };
-
-        postPatch = null;
-      };
-    };
-  };
-in
-
-python.pkgs.toPythonApplication python.pkgs.cynthion
+python3.pkgs.toPythonApplication python3.pkgs.cynthion