Release Kibitz 3.0.0-alpha.1.
Release Kibitz 3.0.0-alpha.1.

 * Add badges to `README.md`. Closes #248.
 * Build with Actions, ship coverage to Codecov. Closes #247. Closes #246.
 * Tidy `.gitignore`.
 * Upgrade `islander` to `5.0.0-alpha.0`. Closes #245.
 * Caret pin dependencies. Closes #244.
 * Upgrade `paxos` to `19.0.0-alpha.4`. Closes #243.
 * Remove Monotonic dependency. Closes #242.

Closes #249.

bigeasy/kibitz,bigeasy/kibitz