Replace .netrc with Env Var in Dockerfile

[jim380]

Overview

This PR attemps to use environment variables in Dockerfile to pass sensitive information like GitHub Personal Access Tokens (PATs) has several advantages over using a .netrc file for the following reasons:

1. Security: Environment variables are ephemeral and only exist for the duration of the Docker build process. They are not stored in any file that could be accidentally committed to a repository or left around on a filesystem

2. Flexibility: Environment variables can be easily changed without modifying any files. This is particularly useful in CI/CD environments where you might want to use different PATs for different builds or stages

3. Portability: Environment variables are a standard feature of all Unix-like operating systems and are supported by all CI/CD systems. On the other hand, the .netrc file is a feature of the netrc library which is not universally supported

4. Best Practices: It's a common best practice in Docker and 12-factor app methodology to pass configuration to applications using environment variables

Tests

• test-e2e

[hacheigriega]

Perhaps we can add a ifdef GITHUB_TOKEN... clause to echo an error message if GITHUB_TOKEN is empty?