fix(installation): allow plugins in installation tests

[damienwebdev]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/graycoreio/magento2-github-actions/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

I fixed integration tests in #12 , and then composer v2.3.9 came out and bit my face off. Turns out, I am my own meme

Fixes: N/A

What is the new behavior?

Installation tests now succeed on v2.3.9.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information