Test components using their lowest possible deps
minor #12542 Test components using their lowest possible deps (nicolas-grekas)

This PR was squashed before being merged into the 2.3 branch (closes #12542).

Discussion
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Test components using their lowest possible deps

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Once https://github.com/composer/composer/pull/3450 is merged, we'll see if our deps are correct, and ensure that is kept over time by testing each component with its lowest possible deps.

Commits
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25fef27 Test components using their lowest possible deps