Update Octokit to v4

[wrslatz]

Is your feature request related to a problem?

Update Octokit to v4. This is required to properly update transitive dependencies that are vulnerable.

Describe the solution you'd like

Octokit v4 migrates to ESM, which is a breaking change. The repo will need to be migrated to ESM (or upgraded to a Node.js version that supports ESM in CJS, which may have compatibility issues for consumers that package the app themselves). Migration to ESM should likely be its own issue.

As part of upgrading, the overrides for @octokit/plugin-paginate-rest added in #330 should be removed.

Describe alternatives you've considered

None. We eventually need to upgrade.

Additional context

No response