add default

flake.nix

@@ -17,7 +17,7 @@
         };
       in
       rec {
-        packages = {
+        packages = rec {
           python = pkgs.python315.overrideAttrs (
             finalAttrs: previousAttrs: {
               patches = previousAttrs.patches ++ [
@@ -33,6 +33,7 @@
               '';
             }
           );
+          default = python;
         };
         devShells.default =
           with pkgs;