move require 'resource' to download_strategy.rb

where it is actually needed

lib/homebrew-fork/Library/Homebrew/download_strategy.rb

@@ -1,3 +1,5 @@
+require 'resource'
+
 class AbstractDownloadStrategy
   attr_reader :name, :resource
 

lib/homebrew-fork/Library/Homebrew/extend/pathname.rb

@@ -1,5 +1,4 @@
 require 'pathname'
-require 'resource'
 
 class Pathname
   # I don't trust the children.length == 0 check particularly, not to mention