Refactor the events list to filter out past events

[rodneybarnes]

Is your feature request related to a problem? Please describe.
The GraphQL query for the events roll currently uses a hard-coded date to filter the requested events; as a result, this needs to be manually changed to remove events from the published page.

Describe the solution you'd like

Instead, I think we can use a .find method after the query is run to filter out the dates (see: https://spectrum.chat/gatsby-js/general/using-variables-in-a-staticquery~abee4d1d-6bc4-4202-afb2-38326d91bd05).

Describe alternatives you've considered

I had thought we could use a variable in the query, but apparently variables do not currently work with StaticQuery components.
[See the above link]

Other options include manually deleting old events from the repo, but this destroys information we may want in the future and is also not as optimal a solution as solving this programmatically.

Additional context

[rodneybarnes]

Fixed with PR #68