GitDownloadStrategy: fix typo'd parameter name

This should be "resource", not "resources", though it works anyway
because there is a also "resource" reader method.

Library/Homebrew/download_strategy.rb

@@ -474,7 +474,7 @@ class GitDownloadStrategy < VCSDownloadStrategy
     %r{http://llvm\.org},
   ]
 
-  def initialize name, resources
+  def initialize name, resource
     super
     @shallow = resource.specs.fetch(:shallow) { true }
   end