[C#][Bot-Solutions] Ignore NU5048 warning

[Batta32]

Fix #3688

Purpose

What is the context of this pull request? Why is it being done?
The NU5048 stops the compilation of C# Bot-Solutions in Azure Pipeline.

Changes

Are there any changes that need to be called out as significant or particularly difficult to grasp? (Include illustrative screenshots for context if applicable.)
Skip NU5048 warning during compilation

Tests

Is this covered by existing tests or new ones? If no, why not?
Yes, it was tested manually and in a pipeline

Feature Plan

Are there any remaining steps or dependencies before this issue can be fully resolved? If so, describe and link to any relevant pull requests or issues.
This solution is the short-term workaround, however, the long-term approach will be to follow the Dotnet SDK specifying PackageIcon and PackageIconUrl to maintain backward compatibility.

Checklist

General

• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the appropriate tests
• I have updated related documentation