(fix): Rm due date on copied campaigns

[shynonagons]

Fixes # (2185)

Description

Remove due_by for copied campaigns to avoid creating campaigns with due dates in the past.

Checklist:

• I have manually tested my changes on desktop and mobile
• The test suite passes locally with my changes
• If my change is a UI change, I have attached a screenshot to the description section of this pull request
• My change is 300 lines of code or less, or has a documented reason in the description why it’s longer
• I have made any necessary changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• My PR is labeled [WIP] if it is in progress