anomiex and matticbot CI: Run tests with PHP 8.1, experimentally (#21207)
54f5724 Oct 26, 2021
CI: Run tests with PHP 8.1, experimentally (#21207)
* Update composer requirement to 2.1

  PHP 8.1 is coming soon, and it makes Composer 2.0 spit out tons of
  deprecation warnings. Plus 2.1 has been out for a while now. Seems like
  a good time to finally update.

* CI: Run tests with PHP 8.1, experimentally

  PHP 8.1 is getting close to release. Let's run tests with it so we can
  start cleaning stuff up.

  This is certainly going to fail a lot of stuff for the moment, as
  WordPress itself is [still working on this][1]. But we may as well get a
  head start on it.

  [1]: https://core.trac.wordpress.org/ticket/53635

* Set `convertDeprecationsToExceptions` true in PHPUnit configs

  PHPUnit is defaulting this to false starting in 8.5.21 and 9.5.10, and
  recommending everyone change their configs to set it back to true.

* Run non-plugin tests when experimental

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/1387011333
54f5724