Update publishing configuration to support the new maven publication process

[overpas]

Closes #127

---

PR-Codex overview

This PR focuses on updating the treemap-chart and treemap-chart-compose libraries for versioning, publication configuration, and enhancing the GitHub Actions workflow for publishing to Maven Central.

Detailed summary

• Changed lib.version from 0.1.2 to 0.1.3.
• Updated id from publication to publish in Gradle files.
• Added maven-publish-plugin dependency.
• Configured mavenPublishing for artifact metadata.
• Enhanced GitHub Actions workflow for publishing, including GPG signing and environment variable updates.

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}