Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

When creating a new action with fastlane new_action, the generated action file contains trailing spaces which are not necessary.

Description

Remove trailing spaces from custom_action_template.rb file. There is no logic and interface changes.

Testing Steps

fastlane new_action