CI 'includes' test is failing

The 'includes' CI test is currently failing with the following error:

```
[RuntimeException]
Failed to execute git clone --mirror 'https://git.drupalcode.org/project/coder.git' '/var/www/.cache/composer/vcs/https---git.drupalcode.org-project-coder.git/'

fatal: could not create leading directories of '/var/www/.cache/composer/vcs/https---git.drupalcode.org-project-coder.git
```

See example build: https://travis-ci.com/github/geerlingguy/ansible-for-devops/jobs/408302188#L402

It fails on the step `Install Drupal dependencies with Composer`, and I'm wondering if it has to do with the very-recent release of Composer 2.

Start with the CI "includes" test and the "Install Drupal dependencies with Composer" step, using the linked Travis build to reproduce the failure. Check whether the Composer version change causes the git clone cache-directory error. The issue is done when the includes CI job installs its Drupal dependencies successfully.

Written by the indexing model from the issue text.