Bump version of vendored `cibuildwheel`

Release v2.3.0 (closeio#134)

Release v2.2.0 (closeio#106)

Update changelog and bump version number

Update CHANGELOG.md

Getting ready for a 2.1.1 release.

Using the release (non-beta) versions of Python 3.7

Merge pull request closeio#43 from movermeyer/raise-valueerror-on-inv…

…alid-dates

Major Rewrite: Raises ValueError on invalid dates