Upgrade to React 19?

[severo]

Currently:

$ npm outdated
Package                 Current   Wanted  Latest  Location                             Depended by
@testing-library/react   16.0.1   16.0.1  16.1.0  node_modules/@testing-library/react  cli
@types/react            18.3.12  18.3.12  19.0.0  node_modules/@types/react            cli
@types/react-dom         18.3.1   18.3.1  19.0.0  node_modules/@types/react-dom        cli
react                    18.3.1   18.3.1  19.0.0  node_modules/react                   cli
react-dom                18.3.1   18.3.1  19.0.0  node_modules/react-dom               cli

React 19 has breaking changes, but to be honest, I don't think we would be affected in any way: https://react.dev/blog/2024/04/25/react-19-upgrade-guide#breaking-changes

[severo]

fixed by #315