ci: harden publish version step

[Shion1305]

Summary

• Fix the version regex used by the publish workflow so it matches pyproject.toml.
• Keep the workflow tolerant when the version already matches the tag.

Context

The publish workflow failed with version field not found in pyproject.toml due to an over-escaped regex. This update uses a clean regex that matches the version = "..." line directly.

Changes

• Use r'(?m)^version\s*=\s*["\']([^"\']+)["\']' to match the version field.

Testing

• local regex check against pyproject.toml