Switch the `JourneySummaryCard` font from Helvetica to Liberation Sans

[idreyn]

The JourneySummaryCard component generates the social media previews for an RRX trip. It is rendered server-side and captured as a PNG. For this reason we need the fonts it uses on our server, and we have accomplished that using the questionably-legal Helvetica Buildpack. Before switching to AWS we'll need to make these changes:

• Include the free font Liberation Sans in this repo
• Modify our CD system to copy it to the server
• Update JourneySummaryCard.tsx to swap out Helvetica for Liberation Sans, Helvetica (this can be tested locally)

[nathan-weinberg]

@idreyn Not sure exactly how we include the font in the repo, but if you can make that change I can make the CD change, then when we do the swap it should deploy onto the AWS instance

[idreyn]

It looks like Helvetica is actually working on Preston's AWS instance (bless up) so no action is required here.