Fix MkDocs Build in CI Pipeline

[jlondonobo]

Overview

This PR addresses an issue where the MkDocs CI Pipeline would fail during the installation of mkdocs-material-insiders due to missing credentials. It potentially resolves issue #49.

Changes

• Ensure credentials are passed during the Install Requirements step by utilizing the GH_TOKEN environment variable.
• Leverage the value stored in secrets.GH_TOKEN to set the GH_TOKEN environment variable.

Configuration

To successfully implement this fix, the following setup is necessary:

1. The repository must have an actions repository secret labeled as GH_TOKEN.
2. This GH_TOKEN secret should correspond to a GitHub token with a minimum access level of the repo scope.