librewolf-unwrapped: add owners

Since the bot does not seem to pick up maintainers for changes to e.g.
`src.json` and so manual review is needed. This should resolve that.

ci/OWNERS

···
 /nixos/tests/snapcast.nix @mweinelt
 
 # Browsers
+/pkgs/applications/networking/browsers/librewolf @squalus @DominicWrege @fpletz @LordGrimmauld
 /pkgs/applications/networking/browsers/firefox @mweinelt
 /pkgs/applications/networking/browsers/chromium @emilylange @networkException
 /nixos/tests/chromium.nix @emilylange @networkException

pkgs/applications/networking/browsers/librewolf/default.nix

···
     description = "Fork of Firefox, focused on privacy, security and freedom";
     homepage = "https://librewolf.net/";
     maintainers = with lib.maintainers; [
+      # Also update ci/OWNERS entry when changing maintainers
       squalus
       dwrege
       fpletz