Upgrade sprockets-rails gem to version 3.0.3
Upgrade sprockets-rails gem to version 3.0.3

`bundle update sprockets-rails`

Upgrades the sprockets-rails gem in smart answers from version 2.3.3 to
version 3.0.3. The major release from 2.x to 3.x introduces breaking
changes, including enabling asset digests by default (JS and CSS files
will receive a checksum value in the in filename).
alphagov/smart-answers,alphagov/smart-answers,aledelcueto/smart-answers,alphagov/smart-answers,alphagov/smart-answers,stwalsh/smart-answers,aledelcueto/smart-answers,stwalsh/smart-answers,aledelcueto/smart-answers,stwalsh/smart-answers,aledelcueto/smart-answers,stwalsh/smart-answers