polarizationsolver: set a pep compliant version string

pkgs/development/python-modules/polarizationsolver/default.nix

···
     hash = "sha256-LACf8Xw+o/uJ3+PD/DE/o7nwKY7fv3NyYbpjCrTTnBU=";
   };
 
+  # setup.py states version="dev", which is not a valid version string for setuptools
+  # There has never been a formal stable release, so let's say 0.0 here.
+  postPatch = ''
+    substituteInPlace ./setup.py --replace 'version="dev",' 'version="0.0",'
+  '';
+
   propagatedBuildInputs = [
     numpy
     periodictable