fix attendance list integration with google sheets data

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Issue

The v3 google sheet api the webguide uses to fetch a listing of attendees is currently broken. This is because the v3 api was deprecated Aug 2021. It is recommended to use the v4 api.

Resources

• https://cloud.google.com/blog/products/g-suite/migrate-your-apps-use-latest-sheets-api
• attempting a fix in https://dashboard.pantheon.io/sites/6c7fdb63-b2c6-4720-9b19-1bc6cca8792f#fix-gsheets