Fix OrderedModelManager warnings in Sponsorship models (#2743)

[MisbahAN]

Overview

This PR resolves the warning (ordered_model.W003) for both SponsorshipBenefit and SponsorshipPackage models. These models subclass OrderedModel but were previously using managers that did not inherit from OrderedModelManager.

Changes Made

• Updated SponsorshipPackage to use OrderedModelManager.from_queryset(SponsorshipPackageQuerySet)()
• Updated SponsorshipBenefit to use OrderedModelManager.from_queryset(SponsorshipBenefitQuerySet)()
• Added necessary import for OrderedModelManager

Why This Fixes the Warning

Using .as_manager() does not ensure that the resulting manager inherits from OrderedModelManager, even if the queryset does. Using .from_queryset() ensures the manager inherits from OrderedModelManager while preserving custom queryset functionality.

Fixes #2743