ckb-next: use deprecate! instead of discontinued

Casks/c/ckb-next.rb

@@ -7,6 +7,8 @@ cask "ckb-next" do
   desc "RGB driver"
   homepage "https://github.com/ckb-next/ckb-next"
 
+  deprecate! date: "2023-12-17", because: :discontinued
+
   depends_on macos: ">= :sierra"
 
   pkg "ckb-next.mpkg"
@@ -16,8 +18,4 @@ cask "ckb-next" do
               "org.ckb-next.daemon",
             ],
             launchctl: "org.ckb-next.daemon"
-
-  caveats do
-    discontinued
-  end
 end