GPIO update 4 --> 21

[jharvey]

Creating a tracker for this to help prevent it from falling through the cracks. GPIO is currently 4, should be 21. See discussion #600

[rjsachse]

Thank you for identifying the issue and proposing a fix! To contribute back to the community, you can create a pull request (PR) with your changes. Here’s how:

Fork the Repository: Clone the project to your GitHub account.
Create a Branch: Make a new branch for your fix (e.g., fix-issue-123).
Commit Your Changes: Add your fix with clear commit messages.
Submit a Pull Request: Push your branch and open a PR, describing the issue and your solution.
Engage with Feedback: Respond to any review comments to refine your contribution.
Submitting a PR not only helps improve the project but also connects you with the community, showcasing your skills and passion. Ready to give back? Let’s get your fix merged!