[Cashtab] Add missing meta field per errors reported by Twitter card validator

Summary: Twitter card validator throws errors indicating the og:title field is required; adding it

Test Plan: npm test to confirm app is not affected, will need to test after deployment to confirm Twitter appearance

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Subscribers: majcosta

Differential Revision: https://reviews.bitcoinabc.org/D9207