ci: tag-triggered PyPI release workflow

[mishanefedov]

Summary

• Adds a v*-tag release workflow publishing unisonlabs to PyPI via Trusted Publishing, matching the four adapter repos. The SDK now deploys by tagging, like everything else.

Test plan

• mirrors the verified langchain-unison release.yml

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Summary by cubic

Adds a tag-triggered GitHub Actions workflow that publishes unisonlabs to PyPI via Trusted Publishing. Releases now happen by pushing a v* tag.

• Migration
  • To release, push a tag like v1.2.3 to main.
  • If Trusted Publishing isn’t enabled, add PYPI_API_TOKEN and enable the commented with: password block in .github/workflows/release.yml.

^{Written for commit 7e98e8e. Summary will update on new commits.}