[HttpKernel] fix composer.json
minor #12078 [HttpKernel] fix composer.json (nicolas-grekas)

This PR was merged into the 2.6-dev branch.

Discussion
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[HttpKernel] fix composer.json

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

This fixes the composer.json of HttpKernel

Commits
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7bb768d [HttpKernel] fix composer.json