tap-unpin: simplify logic

Closes Homebrew/homebrew#43260.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Library/Homebrew/cmd/tap-unpin.rb

@@ -2,10 +2,8 @@ require "cmd/tap"
 
 module Homebrew
   def tap_unpin
-    taps = ARGV.named.map do |name|
-      Tap.new(*tap_args(name))
-    end
-    taps.each do |tap|
+    ARGV.named.each do |name|
+      tap = Tap.new(*tap_args(name))
       tap.unpin
       ohai "Unpinned #{tap.name}"
     end