Yarn warnings

[zfletch]

yarn install generates the following warnings. None of the warnings prevent the application from running, but we should try to get rid of them anyway.

warning " > bootstrap@4.1.3" has unmet peer dependency "jquery@1.9.1 - 3".
warning " > bootstrap@4.1.3" has unmet peer dependency "popper.js@^1.14.3".
warning " > eslint-config-airbnb@17.0.0" has incorrect peer dependency "eslint@^4.19.1".
warning "eslint-config-airbnb > eslint-config-airbnb-base@13.0.0" has incorrect peer dependency "eslint@^4.19.1".
warning " > eslint-config-react-app@2.1.0" has incorrect peer dependency "eslint@^4.1.1".
warning " > eslint-config-react-app@2.1.0" has incorrect peer dependency "eslint-plugin-jsx-a11y@^5.1.1".
warning " > eslint-loader@1.9.0" has incorrect peer dependency "eslint@>=1.6.0 <5.0.0".