fix incorrect path for apt conf file

manifests/os/debian.pp

@@ -111,8 +111,8 @@ class base::os::debian (
       }
     }
 
-    file { '/etc/apt/preferences.d/apt_cache_tmp':
-      content => template('base/os/etc/apt/preferences.d/apt_cache_tmp.erb'),
+    file { '/etc/apt/apt.conf.d/apt_cache_tmp':
+      content => template('base/os/etc/apt/apt.conf.d/apt_cache_tmp.erb'),
       require => File[$apt_cache_tmp_dir],
     }
   }