python3Packages.peppercorn: set license (#516474)

lib/licenses/licenses.nix

@@ -263,6 +263,11 @@ lib.mapAttrs mkLicense (
       fullName = "Lawrence Berkeley National Labs BSD variant license";
     };
 
+    bsd3Modification = {
+      spdxId = "BSD-3-Clause-Modification";
+      fullName = "BSD 3-Clause Modification";
+    };
+
     bsd3ClauseTso = {
       spdxId = "BSD-3-Clause-Tso";
       fullName = "BSD 3-Clause Tso variant";

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

@@ -19,5 +19,6 @@ buildPythonPackage rec {
     homepage = "https://docs.pylonsproject.org/projects/peppercorn/en/latest/";
     maintainers = [ ];
     platforms = lib.platforms.all;
+    license = lib.licenses.bsd3Modification;
   };
 }