Release 1.19.3

[DeeDeeG]

DeeDeeG (2): README.md: Update Slack invite link (#631) yarn.lock: Update elliptic and lodash (#633)

Checklist

• [ ] Tested Mobile Responsiveness
• [ ] Added Unit Tests
• [x] CI Passes
• [x] Deploys to Heroku on test Correctly (Maintainers will handle)
• [ ] Added Documentation (Service and Code when required)

[DeeDeeG]

The squash commit message for this PR should be this (or similar):

* README.md: Update Slack invite link (#631)

  This one apparently will NOT expire.

* yarn.lock: Update elliptic and lodash (#633)