Feature: Support PHP 8.1 and PHP 8.2.
(#47 by @SimonFrings and #52 by @WyriHaximus)

Minor documentation improvements.
(#48 by @SimonFrings and #51 by @nhedger)

Update test suite and use GitHub actions for continuous integration (CI).
(#45 and #49 by @SimonFrings and #54 by @clue)