Close and unlink iso tempfile

On Windows tempfile.delete does not delete the file. It needs
to be closed and unlinked

lib/vagrant/util/caps.rb

@@ -30,7 +30,8 @@ module Vagrant
           if file_destination.nil?
             tmpfile = Tempfile.new(["vagrant", ".iso"])
             file_destination = Pathname.new(tmpfile.path)
-            tmpfile.delete
+            tmpfile.close
+            tmpfile.unlink
           else
             file_destination = Pathname.new(file_destination.to_s)
             # If the file destination path is a folder, target the output to a randomly named

test/unit/plugins/hosts/darwin/cap/fs_iso_test.rb

@@ -62,7 +62,8 @@ describe VagrantPlugins::HostDarwin::Cap::FsISO do
       ).and_return(double(exit_code: 0))
       # Should create a directory wherever Tempfile creates files by default
       expect(FileUtils).to receive(:mkdir_p).with(Pathname.new(file_destination).dirname)
-
+      allow(file_destination).to receive(:close)
+      allow(file_destination).to receive(:unlink)
       output = subject.create_iso(env, "/foo/src")
       expect(output.to_s).to eq(file_destination)
     end