nut: add licenses

pkgs/applications/misc/nut/default.nix

···
       "$out/lib:${neon}/lib:${libusb.out}/lib:${avahi}/lib:${freeipmi}/lib"
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "Network UPS Tools";
     longDescription = ''
       Network UPS Tools is a collection of programs which provide a common
···
     '';
     homepage = http://www.networkupstools.org/;
     repositories.git = https://github.com/networkupstools/nut.git;
-    platforms = with stdenv.lib.platforms; linux;
-    maintainers = with stdenv.lib.maintainers; [ pierron ];
+    platforms = platforms.linux;
+    maintainers = [ maintainers.pierron ];
+    license = with licenses; [ gpl1Plus gpl2Plus gpl3Plus ];
     priority = 10;
   };
 }