tap-unpin: Use CLI::Parser to parse args

Library/Homebrew/cmd/tap-unpin.rb

@@ -1,10 +1,25 @@
 #:  * `tap-unpin` <tap>:
 #:    Unpin <tap> so its formulae are no longer prioritized. See also `tap-pin`.
 
+require "cli_parser"
+
 module Homebrew
   module_function
 
+  def tap_unpin_args
+    Homebrew::CLI::Parser.new do
+      usage_banner <<~EOS
+        `tap-unpin` <tap>
+
+        Unpin <tap> so its formulae are no longer prioritized. See also `tap-pin`.
+      EOS
+      switch :debug
+    end
+  end
+
   def tap_unpin
+    tap_unpin_args.parse
+
     ARGV.named.each do |name|
       tap = Tap.fetch(name)
       raise "unpinning #{tap} is not allowed" if tap.core_tap?