Fix Update erb_template_helper.rb with require 'ostruct' to solve uninitialized constant Fastlane::OpenStruct (NameError)

[nicgodoy]

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 see several green ci/circleci builds in the "All checks have passed" section of my PR (connect CircleCI to GitHub if not)
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.
• I've added or updated relevant unit tests.

Motivation and Context

Resolves #21944

Description

Added missing require 'ostruct' on erb_template_helper.rb to solve error:

/usr/local/lib/ruby/gems/2.7.0/gems/fastlane-2.220.0/fastlane/lib/fastlane/erb_template_helper.rb:20:in module:Fastlane': uninitialized constant Fastlane::OpenStruct (NameError)

Testing Steps

[brianhsux]

when will this issue be solved?