pdfminer: fix missing package version

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

@@ -21,6 +21,12 @@ buildPythonPackage rec {
     done
   '';
 
+  postPatch = ''
+    # Verion is not stored in repo, gets added by a GitHub action after tag is created
+    # https://github.com/pdfminer/pdfminer.six/pull/727
+    substituteInPlace pdfminer/__init__.py --replace "__VERSION__" ${version}
+  '';
+
   checkInputs = [ pytestCheckHook ];
 
   meta = with lib; {