[Cashtab] Running npm upgrade

Summary:
T2678

Running npm upgrade to update peer dependencies

The upgraded eslint caused npm run build to fail due to some lint errors. These are also corrected.

Test Plan:
npm run build make sure it still builds
npm start and make sure the app is working ok

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12007