Add GitHub Action to validate entries

[rollquaye]

• Add GitHub Action to validate entries

This updated code adds a new GitHub Action workflow for validating entries. The workflow runs on every push and pull request to the main branch, using Python 3.9 on Ubuntu. It then installs necessary dependencies and runs a script to validate the entries.

• Refactor formatting for GitHub Action validation workflow

This code revision doesn't introduce new functionality; it merely refines the formatting within the GitHub Actions validation workflow file. It precisely adjusts the structure around the "main" branch triggers, ensuring a cleaner, more readable workflow definition.