chore: update spec.types.ts from upstream

[github-actions]

This PR updates packages/core/src/types/spec.types.ts from the Model Context Protocol specification.

Source file: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5c25208be86db5033f644a4e0d005e08f699ef3d/schema/draft/schema.ts

This is an automated update triggered by the nightly cron job.

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