chkcrontab: migrate to pyproject (#519580)

pkgs/by-name/ch/chkcrontab/package.nix

@@ -1,21 +1,27 @@
 {
   lib,
-  python3,
+  python3Packages,
   fetchPypi,
 }:
 
-with python3.pkgs;
-
-buildPythonApplication (finalAttrs: {
+python3Packages.buildPythonApplication (finalAttrs: {
   pname = "chkcrontab";
   version = "1.7";
-  format = "setuptools";
+  pyproject = true;
 
   src = fetchPypi {
     inherit (finalAttrs) pname version;
     sha256 = "0gmxavjkjkvjysgf9cf5fcpk589gb75n1mn20iki82wifi1pk1jn";
   };
 
+  postPatch = ''
+    # cannot install the manpage as it is not present in the wheel
+    substituteInPlace setup.py \
+      --replace-fail "'doc/chkcrontab.1'" ""
+  '';
+
+  build-system = [ python3Packages.setuptools ];
+
   meta = {
     description = "Tool to detect crontab errors";
     mainProgram = "chkcrontab";