Add branch protection to `main`

We should add branch protection to the `main` branch. This will mirror other repositories within the org. This would prevent merges to `main` without a PR review approval.

I've accidentally pushed to main in the past, which if there was a branch protection, this would have been reverted.

This would prevent accidental pushes to main and merging of PRs without approvals.

This is a repository settings change, not a code change. Look for branch protection settings in the repository's settings on GitHub. The goal is to configure protection for the 'main' branch to require pull request reviews before merging and to prevent direct pushes. Check if there are existing GitHub Actions workflows or documentation about repository standards in the org.

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