chore: bump version to 0.2.0-alpha.6

[felixweinberger]

Bump to 0.2.0-alpha.6 to publish #361.

Motivation and Context

Ships the auth callback iss / metadataIssuer fix (#361) to npm under the alpha tag so downstream SDK CI can pick it up.

How Has This Been Tested?

Version bump only; CI runs the full suite on this PR.

Breaking Changes

None.

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

After merge: dispatch .github/workflows/ci.yml on main with publish_alpha=true to publish to npm.

[pkg-pr-new]

Open in StackBlitz

npx https://pkg.pr.new/@modelcontextprotocol/conformance@362

commit: e537ef3