Don't try to store an Alegre package for an item of "blank" type.

[caiosba]

Description

This commit fixes an error reported by Sentry.

Fixes: CV2-6150.

How has this been tested?

TDD. I reproduced it in a unit test that passed after the fix:

$ docker-compose exec api bundle exec ruby test/models/bot/alegre_4_test.rb -n /package/

Error:
Bot::Alegre4Test#test_should_not_try_to_store_package_for_blank_item:
NoMethodError: undefined method `store_package_' for Bot::Alegre:Class
Did you mean?  store_package
               store_package_text

Checklist

• I have performed a self-review of my own code
• I have added unit and feature tests, if the PR implements a new feature or otherwise would benefit from additional testing
• I have added regression tests, if the PR fixes a bug
• I have added logging, exception reporting, and custom tracing with any additional information required for debugging
• I considered secure coding practices when writing this code. Any security concerns are noted above.
• I have commented my code in hard-to-understand areas, if any
• I have made needed changes to the README
• My changes generate no new warnings
• If I added a third party module, I included a rationale for doing so and followed our current guidelines