znc: add missing licenses (#459856)

pkgs/applications/networking/znc/modules.nix

@@ -138,6 +138,8 @@ in
       description = "ZNC FiSH module";
       homepage = "https://github.com/oilslump/znc-fish";
       maintainers = [ ];
+      # has no license
+      license = lib.licenses.unfree;
     };
   };
 
@@ -215,6 +217,8 @@ in
     meta = {
       description = "ZNC privmsg module";
       homepage = "https://github.com/kylef/znc-contrib";
+      # has no license
+      license = lib.licenses.unfree;
     };
   };