Add support for React 18

[felixmosh]

Added React 18 as peer deps and tested it.

• Title is human readable, as it will be included directly in CHANGELOG.md when we do a release
• If this is a new user-facing feature, documentation has been added to API.md

@rkuykendall wdyt? should we trust ower tests? :]

[rkuykendall]

@felixmosh I think so. If something fails, we can add a new test! I'd remove the build artifacts from this though as they are generated on release.

[felixmosh]

Done :]