chore: remove unused NuGet package Uno.SourceGenerationTasks

[Soap-141]

GitHub Issue: #

Proposed Changes

• Bug fix
• Feature
• Code style update (formatting)
• Refactoring (no functional changes, no api changes)
• Build or CI related changes
• Documentation content changes
• Other, please describe:

What is the current behavior?

Uno.SourceGenerationTasks is referenced.

What is the new behavior?

Uno.SourceGenerationTasks is not referenced.

Impact on version

• Major (Public API was modified.)
  • Public constructs (class, struct, delegate, enum, etc.) were removed or renamed.
  • Public members were removed or renamed.
  • Public method signatures were changed or renamed.
• Minor (Public API was extended.)
  • Public constructs, members, or overloads were added.
• Patch (Public API was unchanged.)
  • A bug in behavior was fixed.
  • Documentation was changed.
• None (The library is unchanged.)
  • Only code under the build folder was changed.
  • Only code under the .github folder was changed.

Checklist

Please check that your PR fulfills the following requirements:

• Documentation has been added/updated.
• Automated Unit / Integration tests for the changes have been added/updated.
• Updated BREAKING_CHANGES.md (if you introduced a breaking change).
• Your conventional commit are aligned with the Impact on version section.

Other information