How to run PHPUnit tests?

There is already a docs page about this:
https://www.drupal.org/docs/testing/phpunit-in-drupal/running-phpunit-tests

I've tried to follow that, including creating a browser_output directory and setting up the configuration file (phpunit.xml).

But #2 in the instructions is a stumbling block. It says:

Use a development snapshot (for example, 8.8.x-dev) instead of a tagged release for your development site.

Fine, but it does not tell you how to to this.

So far I've tried the following two commands:

composer create-project 'drupal/recommended-project:8.9.x' web
composer create-project 'drupal/recommended-project:8.9.x' --dev web

Both commands downloads the development version of the core and installs the project – but there is no vendor/bin/phpunit.

I am able to install PHPUnit in a separate step, i.e.:

composer require phpunit/phpunit

However, this installs 9.2.5, which I suspect is too bleeding edge for Drupal 8.9, as every attempt to run a test produces:

PHP Warning:  Class 'PHPUnit\Framework\MockObject\Matcher\InvokedRecorder' not found in /var/www/web/core/tests/bootstrap.php on line 197
PHP Warning:  Class 'Drupal\TestTools\PhpUnitCompatibility\PhpUnit9\HtmlOutputPrinter' not found in /var/www/ca8.roztr.org/web/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinter.php on line 15
PHPUnit 9.2.5 by Sebastian Bergmann and contributors.

Could not use "\Drupal\Tests\Listeners\HtmlOutputPrinter" as printer: class does not exist

Googling these error messages seems to indicate that there is a version mismatch (but I may be wrong about that).

So the question is: How to install Drupal 8 with PHPUnit, in order to run PHPUnit tests afterwards. I seem to need more detailed instructions than those that exists on the linked docs-page.

Environment: Ubuntu 20.04 LTS (i.e. PHP 7.4).