Docusaurus v3.9.1: Update GitHub Actions Example to Point to Node 20 Instead of 18

[egrosdou01]

Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Description

Referring to the documentation here, the GitHub Actions example needs to be updated to reflect the Node version dependencies.

Update node-version: 18 references to node-version: 20.

Self-service

• I'd be willing to address this documentation request myself.