Fix Incremental Static Regeneration & Convert to App Router

[breezyfasano]

Background

Currently, the site uses the pages router for the entirety of the site, with the getStaticProps() function to fetch and serve Eventbrite data. This is possibly why Incremental Static Regeneration stopped working. Netlify updated their runtime for this feature around the time the functionality stopped working, so it's probably best to get this updated and utilizing newest Next functionality.

Main issue

The Events page is not automatically updated when a new eventbrite is created anymore,

Proposed Fix

Convert the site to use the _app router and update any data fetching calls, particularly on /events.