fix(publish): validate MCP distributions with Twine 7

[acedatacloud-dev]

Summary

• Upgrade Twine to >=7,<8 in both build validation and upload steps for six standalone MCP publish workflows.
• Fix the metadata 2.4 validation failure that prevented hCaptcha, Image2Text, reCAPTCHA, Turnstile, and Discord Bot PyPI releases. Include DigitalHuman to keep its identical workflow compatible.

Validation

• actionlint on all six workflow files: passed.
• YAML parsing and two Twine constraints per workflow: passed.
• Python 3.12.13 build and Twine 7.0.0 check: all six source distributions and wheels passed. The four packages failing on 2026-10-08 were built in isolated environments.
• git diff --check: passed.

Rollout

• After merge, sync-to-repos.yml should copy the six workflow changes to the standalone repositories. Verify each sync and ensuing Publish to PyPI run, then check PyPI versions and wheel metadata.
• If PyPI rejects an upload after metadata validation, inspect that exact error and fix it separately. No credentials are included in this PR.

Review

• No adversarial review requested. This change only updates the compatible Twine version range.