[feat!]: Drop support for unsupported Node versions (10.x -12.x at time of creation)
Is your feature request related to a problem? Please describe.
We only test for supported versions (14.x - 18.x at the time of writing), since older versions of Node are not supported. We should explicitly drop that support under engines in package.json. This is, by our definition, a breaking release (for consumers who are not on up-to-date node versions.
relevant PR comment: https://github.com/trussworks/react-uswds/pull/2113#discussion_r879840894
Describe the solution you'd like
Explicitly show which range of node versions are supported, and make sure those are the versions that are tested.
Describe alternatives you've considered
We could leave it in place, but I imagine we don't want to leave any doubt in what versions we maintain the library for.