flake: fix missing setuptools imports

flake.nix

@@ -9,9 +9,21 @@
     overlay = nixpkgs.lib.composeManyExtensions [
       poetry2nix.overlay
       (final: prev: {
-        frontpage = prev.poetry2nix.mkPoetryApplication {
+        frontpage = prev.poetry2nix.mkPoetryApplication
+          {
             python = prev.python39;
             projectDir = ./.;
+            overrides =
+              prev.poetry2nix.overrides.withDefaults (final_: prev_:
+                nixpkgs.lib.listToAttrs
+                  (builtins.map
+                    (name: {
+                      inherit name;
+                      value = prev_."${name}".overridePythonAttrs (old: {
+                        nativeBuildInputs = (old.nativeBuildInputs or [ ]) ++ [ final_.setuptools ];
+                      });
+                    })
+                    [ "beaker" "flask-pyoidc-oda" "oic" ]));
           };
       })
     ];