ci: publish package using npm trusted publisher with OIDC

[pedro-martins-brisa]

Description

This pull request updates the release workflow to clearly separate the build and publish steps using different Node versions.

The project build remains on Node 12.22.1 to preserve compatibility with legacy dependencies, while the npm publish step is migrated to Node 20, which is required to properly support modern npm features such as OIDC authentication and provenance (--provenance).

This change improves the security and reliability of the release process without impacting the existing build behavior.

Compliance

• I have verified that this change complies with our code and contribution policies.
• I have verified that this change does not cause regressions and does not affect other parts of the code.

References

• GitHub Actions – setup-node documentation
• npm documentation – Provenance and OIDC publishing