minor symfony#50570 [GHA] Remove deprecations-baseline (nicolas-grekas)

This PR was merged into the 5.4 branch.

Discussion
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[GHA] Remove deprecations-baseline

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

Doctrine's deprecation layers should be fixed now.

Commits
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39c3f8d [GHA] Remove deprecations-baseline

Author: nicolas-grekas