fix: fix generating load trigger notification when itemCount is less than prefetchIndex.

[xsahil03x]

Description

This pull request includes changes to improve the handling of load trigger notifications and updates to the changelog. The most important changes include fixing the generation of load trigger notifications when the itemCount is less than prefetchIndex and updating the changelog to reflect this fix.

Improvements to load trigger notifications:

• lib/src/widget/bidirectional_paging_list_view.dart: Fixed the generation of load trigger notifications when itemCount is less than prefetchIndex by adding conditions to handle this case and updating the logic for checking indices.
• lib/src/widget/paging_sliver_list.dart: Added similar logic to handle the case when itemCount is less than prefetchIndex and updated the conditions for generating load trigger notifications.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore