Install of phpstan always times out

Problem/Motivation

Trying to install the module

Steps to reproduce

- Installing mglaman/composer-drupal-lenient (1.0.6): Cloning 78aa8780da from cache
  - Installing wikimedia/composer-merge-plugin (dev-feature/composer-v2 b8b8cb4): Cloning b8b8cb4db4 from cache
  - Installing phpstan/phpstan (1.12.10): Cloning fc463b5d0f from cache
    Install of phpstan/phpstan failed
The following exception is caused by a process timeout
Check https://getcomposer.org/doc/06-config.md#process-timeout for details

In Process.php line 1205:

  The process "git clone --no-checkout '/root/.cache/composer/vcs/https---github.com-phpstan-phpstan.git/' '/srv/www/htdoc
  s/www/vendor/phpstan/phpstan' --dissociate --reference '/root/.cache/composer/vcs/https---github.com-phpstan-phpstan.git
  /' && cd '/srv/www/htdocs/www/vendor/phpstan/phpstan' && git remote set-url origin -- 'https://github.com/phpstan/phpsta
  n.git' && git remote add composer -- 'https://github.com/phpstan/phpstan.git'" exceeded the timeout of 300 seconds.

But I have

    "scripts": {
        "test": [
            "Composer\\Config::disableProcessTimeout",
            "phpunit"
        ]
    }

in my composer.json

Proposed resolution

It takes many tries to get this to work, all with long waits.

Remaining tasks

User interface changes

API changes

Data model changes