Run `file.close` before unlinking for travis

This works on OSX but for some reason travis is throwing a
```
  1) Error:
ExpiresInRenderTest#test_dynamic_render_with_absolute_path:
NoMethodError: undefined method `unlink' for nil:NilClass
```
Looking at other tests in Railties the file has a name and we close
it before unlinking, so I'm going to try that.

1 files changed, 2 insertions, 1 deletions

diff --git a/actionpack/test/controller/render_test.rb b/actionpack/test/controller/render_test.rb
index 2e1a687513..9430ab8db8 100644
--- a/actionpack/test/controller/render_test.rb
+++ b/actionpack/test/controller/render_test.rb
@@ -271,13 +271,14 @@ class ExpiresInRenderTest < ActionController::TestCase
   end
 
   def test_dynamic_render_with_absolute_path
-    file = Tempfile.new
+    file = Tempfile.new('name')
     file.write "secrets!"
     file.flush
     assert_raises ActionView::MissingTemplate do
       response = get :dynamic_render, params: { id: file.path }
     end
   ensure
+    file.close
     file.unlink
   end