fix: replace deprecated dev-dependencies in examples/clients

[yukuanj]

Motivation and Context

With the newest version uv 0.9.5 (d5f39331a 2025-10-21), uv gives the warning

warning: The tool.uv.dev-dependencies field (used in ...) is deprecated and will be removed in a future release; use dependency-groups.dev instead.

This is a continued effort following #1488, replacing the deprecated dev-dependencies with dependency-groups in server examples examples/clients/.

How Has This Been Tested?

I have tested in MacOS 15.5 with uv 0.9.5 (d5f39331a 2025-10-21).

Breaking Changes

No breaking changes.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context